Try and get a stop off in the tropics , you will find prices in Sydney very high compared with up here .
Winter is pretty cold there and any real tropicals will be dead as doornails. You will find some Orchid Nurseries , but most are miles out of town due to high price for land .
Cheap airfare3 up here to Cairns will only be approx $150 ..
good luck Calvin

Palmland Nursery in Terry Hills are one of the best for rainforest plants, natives, palms and ferns. They get stuff shipped down from the north quite regularly. Attached to Palmland is one of the Sydney Wildflower nurseries which has an huge number of native plant species. Next door is a supplier of all things for Japanese gardens, from bamboos to sculptures to all sorts of great stuff. There is a restaurant there set in a truly fantastic Asian garden including beautiful waterfalls and ponds full of Koi carp. It is certainly worth a visit.

Impact Nursery up on the Central Coast are also very good.

If you are after orchids, you would be wise to get in touch with the various orchid societies which abound in Sydney. You can then go along to one of their meetings if one takes place during your visit and either buy plants thru the sales table or meet the members and buy directly from them. Most do grow other tropical plants besides orchids. And some like myself are very reasonable.
It's true that you will find a lot of variety further up north and some sellers are fair but I did find some sellers there rather expensive. You have to be selective where ever you go. Some people are only in plants for the money and will rip you off given the opportunity. You will know these people almost immediately from the prices they charge, the size of the plants they sell and the so called rarity of the plants they sell. I have to say that my tropical plants are doing very well and a lot of other tropical plants growers that I know of in Sydney have no problems either with a wide variety of tropical plants.

I can see that you are a collector of unusual species. If I were you, I would go to Cairns. You can find most things that are not available anywhere else in Cairns, especially tropical plants like heliconias, calatheas and other stuff you are interested in.

Even I have to go to Cairns to pick up a few rare stuff. Things are usually cheaper in Cairns than down south. I know, because I used to live in Brisbane.

Good luck with the shopping trip.

Regards, Ari :)

Impact Plants at Empire Bay near Gosford has a good selection of tropical plants including helconias crotons etc. It also has an extensive landscaped tropical garden which is well worth a visit