In talking to companies about the RFQ-to-Bid (or Request-to-Quote) process, we found that they are faced with the following challenges:
a) Ability to tap into in-house intelligence about past projects, whose bids can be leveraged to quickly turn-around a bid for a new RFP
b) The usual gap between the customer's actual needs, communicated needs and quoted requirements
It'd be interesting to hear about what other challenges do companies face in this process, and what are some of the common tools that they use to capture requirements, collaborate with customers and generate bids.
You could take a look at http://www.mie-exchange.com which is a made to order RFQ - Bid - PO systems. This is not an open bidding system like ebay, etc. Its more to help your current communication between buyers/suppliers. It has an open api so data can be pushed and pulled from the system.