Just check the seeds to make sure they are fresh. Many seeds must be sown fresh to germinate and a lot of eBay seedspeople buy in bulk from the big companies and repackage. So the facts that you need to consider are - do you know how old they are, have they been stored at low temps?
Some people collect from their own garden and cross pollination may have occurred so may vary from the parent.
I bought some at one stage and had zero germination. (I am experienced at seed raising so am familiar with all the tricks of the trade etc.)
Seeds that I have bought from big dealers (Jellito etc) have always been excellent.

Descriptions are a good guide line. If the seller sounds knowledgeable and gives you plenty of information, it's a safe bet that they know how to harvest and store the seeds.
I bought hellebore seeds from tas - they are on offer again I see. They were special hand pollenated varieties, and I paid $4 for 10 seeds - $16 for 4 packets, 40 seeds in all. For my money I got 16 plants - some of each variety. I know they will be gorgeous and should probably bloom next year from seed planted last winter. I feel that my money was well spent, and would buy from the same vendor again.
I bought Iris missouriensis seed from an Aussie seller, and got very little seed in the pack - and later discovered an american seller using the exact same photo, selling them in bulk for mot much more. My guess is the aussie seller bought from the US, then re packed them.
I ignore the sellers that tout their seeds as "rare" especially when I see common plants with weed potential described that way, and perhaps it is a good thing that their packs only contain 10 or so seeds :-(
As lomatia says - you will get to know the sellers. If I see someone selling something unusual that I particularly want, I will ask them what else they have to offer me that they might not have put up for sale on e-bay. I have nad some nice free extras, and also found and purchased some nice rarities that way.
Paypal? Not for buying in Aus. Just use direct deposit if you can. If you use online banking it is fast and easy. Even if you have to go to the bank it's the cheapest option, compared with cheques (takes time and many won't accept) concealed cash (risky) and money order (costly).
Buy several packs from the one vendor if possible, as this saves on postage.
Beware of buying from overseas. Make sure what you buy is permitted in AUs, and the vendor is prepared to package it to suit out quarantine requirements.
I have only ever once had a parcel not arrive from an e-bay seller, and that was a cross stich pattern from someone who sold heaps of stuff, and had obviously thought he had sent, but hadn't.
Good luck and happy bidding,
Cheers, Jan

Check feedback on the seller.
What I've done, too, is contact a previous buyer and asked personally about their experience.
Annie

A few of the sellers in Aus buy from overseas and re package and I think some of the seeds have been through more than one wholesaler before you get them. Some of the sellers clearly dont know much at all about what they are selling, or dont care. I agree if it is RARE dont bother unless it is a seller who specialises in one partiular type of plant ie bulbs, succulents etc. If you want to get an idea where the seed really come from check out the "from sellers" feedback for the person you are considering buying from. I have had some great purchases and have been well and truly taken for a ride by some other sellers but all the specialist sellers have sent good viable seed, and have been very helpful with advice and germination tips. I still havent used paypal. I Just send hidden cash for os purchases after checking that the seller is ok with it. Would rather lose $5.00 than have the hassle with security that could occur with other methods. Beware of enticing descriptions that dont give proper botanical names. Some of the plants being promoted this way are potential noxious weeds and I have even seen some very nasty declared weeds offered.

I've never even thought of checking eBay for seeds or plants - might take a look.

Thought I might mention this while there's an eBay discussion going on, recently my husband was bidding on something and towards the end of the auction, it basically was a bidding war. Hubby won the auction and subesquently got an email from the seller BUT he noticed that the account name wasn't the same as the item was under. The seller had another account name which was the same as the person my husband was bidding against,he was bidding for the item to bring up the price. DH emailed him to tell him that under those circumstances he would not be paying, then left negative feedback and reported the guy.

Hi
I have just bought some plants and seeds from ebay. I found with the auctions the price goes up quickly. what I am concerned about is the postage. Most ebayers will happily combine items to save on postage. I have only received one packet of seed so far but am expecting other plants etc. I used to buy faitffully from a nursery here but after losing a lot of plants, decided to give them a big miss. I do buy from our local Mitre 10 and a landscaping place now. Will post when my other things come through from ebay and let you know how they go.Jan

Mixed reaction.
I've been using Ebay to buy plants/seeds for around 3 years now. You get to know the goodies/baddies purely from experience. Only 2 really bad experiences, both of whom I had to chase up for delivery, and both really nasty customers - can't name them here. Overall though, I find the seeds are cheaper than elsewhere, and quite a few sellers throw in 'freebies'. I do use Paypal, where available, otherwise direct-debit or hidden cash (within Australia).
I usually buy 'buy it now'items, rather than auctions, unless it's something I really, really want, then wait til the last 30 seconds and jump in.
So, perhaps, overall, I must say I love Ebay, even though you might spend hours just ploughing through it all.
The only drawback, I've found, is that although some give propagation hints, not many tell you when to actually SOW the seeds in your particular area. I know you can look it up on the net, but a lot of the seeds aren't there.
May I add that the Garden Exchange here is just as good?
Cheers, Venice

Have only had one really nasty experience with E-bay but probably my own fault. I attempted to point out that Japanese iris were most unlikely to be protected by PBR. Really none of the iris breeders in aus do that! Also that no law in aus prevented a person from giving the registered name of an iris. My suspicion was that they were seedlings as the actual photo of the sale item was not being given. The irises were priced rediculously high, and the postage was also way high. She was extremely nasty back to me, and put my comments up on e-bay which of course was the last thing she should have done because it would have lost her sales, if any one was even interested at those prices.
As far as the exchange here being better than e-bay - I beg to differ. I have had some fabulous stuff from e-bay (seeds that is). Some nice stuff here, but generally not of much interest to me anyway.
I think the best place to go for seeds is specialist groups, such as SIGNA and the alpine plant groups, if you are looking for special little bits and pieces.
Common plants are best bought in Aus rather than from O/S sources. There are plenty of catalogues (Diggers, New Gippsland, etc) who will probably have seeds for prices as good as those offered on e-bay. Watch closely for people who advertise a plant (say siberian iris at present on e-bay) and in the small print it tells you that you will get 1 seed, or 10 seeds, or whatever, rather than the plant that is advertised. Also if something is advertised as rare check out that it is not infact a weed. There are a couple of these on e-bay right now at crazy prices.

Misleading advertising can be a problem, too, as I discovered when the vine peach melon seeds advertised on ebay as having a 'peach or mango' flavour turned out to be a bland variety suitable only for pickling. (Bought from a seller with a large number of positive feedback scores, too.) Alas, I wasted three months of care, labour and watering on the plants before I discovered this, and the ebay feedback/complaints mechanism is limited to a period of 60 days after purchase. So the seller continues to have an unblemished record on ebay.

Then there's the perennial problem of seeds that fail to germinate, because you can never be certain if it's something lacking in the germination conditions you've provided, or because the seeds were duds.

Of course with the specialist society seedlists one of the commonest complaints is that what you get may not be what you were led to think it was. Especially frustrating to lavish care on a rarity which turns out to be something common (though it builds character I suppose). Established suppliers of specialist seeds, such as the Archibalds, are more reliable - if they have what you want it may be worth paying a little more rather than waste time and energy.

kayman - please enlighten us re archiblads. I did a search on google and saw mantion of them but no web page. Sounds interesting :-)
Cheers, Jan

The Archibalds were meant only as an example, though they're more easily accessible (the link below is to their website) than, say, Flores & Watson.

The only word of caution I have about the Archibald's seeds is that some of the wild-collected items, for obvious reasons, may not have a good germination rate.

Here is a link that might be useful: JJA Seeds