To me it is pretty simple. If these transactions are to take place confidentially, then there should be no policy to force anyone to put a price down period. Prime requires that when you list an item for sale, it should have an asking price. Therefore, the asking price is not a private and confidential thing and should remain that way. If someone does not like that, they are certainly free to sell their items elsewhere.
Agreed. This is a free service, and if you don't like the terms (part of which is listing your asking price), sell your stuff elsewhere. Listing and then deleting the price contributes to the community how exactly?