Prices at Repticon will be right around market value, perhaps a little lower. I suggest to secure yourself a sale, look at the vendors and pre-buy.
Now as for the seller you were already planning to buy from, did you send some sort of deposit? Or some sort of written agreement? Maybe it's just me, but as a seller, if I say I'm going to hold something, I'm going to hold something. If not I'd tell the buyer that I can't hold it.