You could also add a "notes" section to the offers - there is a site that runs like this called IOffer, where a seller lists something but buyers can bid under and post a message with the bid. This way a buyer could say "hey I want this, but I'll pay 8btc instead of 10", and the seller can say "sure I will do this if you direct send the funds to me instead of tying them up in escrow for 3 weeks". The option for escrow is good but I personally won't be discounting anything through escrow. If someone wants to send me the funds immediately so I can revert them back to my float I am definitely going to cut them a deal, basically street price + package/shipping.Also, to let buyers know a seller's price-flexibility, a seller could check an option to display previous price deals (does not have to display username of buyer, just completely transactions at price). As a seller, if it is going to entice more buyers to my product and open up payment terms I am all for it, even if my margins drop.