Print Quote Bidding Script

We are looking for a programmer to create an online interface that allows print buyers to post their print requirements allowing print sellers to bid on them individually. The buyers would create a buyer account and the sellers would create a seller account. The buyer listing would ask for various information about the print quote they require like quantity, colours, stock etc., once submitted the sellers can bid on each job and ask for more information if needed. The buyer can then select a seller from all the bids available. I would like a fairly simple version to start with but i would also like it to be scalable in the future. Hope this is enough info to get on with