A fella might die the slow death of too many PM's...
Might go like this:
Seller: I've got this rare thing that I know would be great for your collection that I would like to sell for as much as possible. You decide how much is possible, PM me.
Buyer: What is it?
Seller: It's rare, NOS probably, with some specks.
Buyer: Any pics?
Seller: I'd like to keep the playing field level by not supplying pics. PM me if you want some fuzzy pics.
Buyer: I'll give you a thousand dollars for it site unseen if you get it in the mail tomorrow.
Seller: That would not be fair to the others who may be interested, but I'll get back with you in a couple of weeks...