Short answer - no. Market value is what the market is prepared to pay.

In general, wholesale growers will offer the same plants of similar sizing at a similar price range, given regional variations and their costs. Then it is up to the retailers to price it to market. And that can be all over the board. The larger, older or more mature the specimen, the higher the price goes, to reflect either the rarity of a plant that size and/or the costs/time incurred by the grower in getting it to that size.

Since the vast majority of plants are sold long before they reach a mature size and age, the inventory of those that are allowed to reach a full size is limited, so the "rarity" of a fully sized, mature specimen is a big factor. Obviously, the popularity or commonness of the plant in question will have a major influence on price as well.

But no, there is no "blue book" or published pricing guide.

@Revolutionary Gardens I would like to check out those broker services that you referenced. If you cannot publish the links in public you could send me a message through Gardenweb.

@gardengal48 It is amazing to me that no one has tried to create such a guide. I think nurseries would have a strong incentive to participate in such a service and provide their own data on plants, with the common industry goal being to help better define market opportunities. By providing its limited market view, each nursery would be getting back a wealth of information about plants they have never stocked or commonly sold.

Part of such a guide would be to establish regional markets. Obviously a huge Euphorbia has many potential buyers in Arizona and almost none in Alaska.

Another obvious part of having such a guide would be to show market opportunities where there is a lot of demand but very little supply.

Having been a participant in both the wholesale and retail end of the nursery industry (and as a buyer on the retail end) for going on 3 decades, I can say with some degree of assurance that no nursery owner I have ever encountered would be interested in such a reference or be bound by that sort of specified pricing structure!! Independent nursery owners will always prefer to call their own shots and make their own pricing decisions.

btw, brokers will price according to charges levied on them by the growers. Unless you are buying in bulk - like a truckload - you are not going to be getting any great bargains. They will be pricing at local retail market rate as well.

@gardengal48 That's like saying no car dealer would ever want to know Blue Book pricing on used cars and would prefer to just call their own shots. The nursery that gets in some rare large cactus and just "shoots from the hip" and puts a $500 price on it might feel very good about their independence, but they will not feel great when the Blue Book would have told them it sells in the Southwest for $6000. There is no way that any wholesaler or nursery could ever accumulate a total market view for rare large plants, and honestly, they are a little arrogant if they believe they could do that on their own. It is a big world and some of these plants are rare enough at a large size that a given nursery may never see one.

"It is a big world and some of these plants are rare enough at a large size that a given nursery may never see one."

That is perfectly correct. But the nurseries that DO deal in these sorts of plants are well aware of the going rate. There is no "shooting from the hip" - this is a very incestuous industry and each specialty grower or dealer knows what their competition is charging.

And there is a far greater risk of a nursery/retail seller assigning a higher than market or premium price tag to a specimen quality plant than one that is significantly (or maybe even just slightly) under market.

Not to mention that customer tastes can be very mercurial. What is insanely popular one year may be almost impossible to "give away" the next. I've seen this at plant shows wherein at one show a particular type of plant practically flies off the tables, but at the next show a few cities over, they just sit there.