[consulting] best course of action question

[Jeremy Weiss]

I have a project coming up that I'd like to use Drupal for. However, I have a bad habit of trying to make one tool fit all situations so I was wanting some outside eyes on it.

The site would be a middle man between buyers and sellers of a certain widget. Both the buyers and sellers would need to register to use the site. It would be free to buyers to register but sellers would have to pay a subscription fee.

The simplistic overview would be something like this:
When they register, sellers would choose which states they wish to solicit business in. The buyers would fill out a RFQ form which would be automatically sent to all the sellers who are registered for the state the buyer specified in the form. The sellers would respond to the RFQ with a quote. The buyer would then choose a seller with which to do business.

Now, I like Drupal for this project b/c of the ease of rolling out the members system and the existing modules would take care of most of the client's requirements. But I'm not exactly sure how to go about creating the system to pass the RFQ data back and forth. Would this be an area where I'd need to write a custom module or are there existing modules that would take care of this? Or am I trying to hammer a screw and need to lay down my Drupal hammer and go find a screwdriver?

Thanks,
Jeremy