shri - 3:44 am on Apr 28, 2011 (gmt 0)

Switch modes and take the order yourself. Send your supplier payments every 30 days and send them the orders via EDI / XML.

Will involve some extra steps but it will give you a lot more control over the user experience and will allow you to broker orders more effectively. (At the end of the day, this is what Amazon and pretty much everyone else is doing... taking orders and send them to their wholesalers / distributors who are doing the fulfillment.)