Install auction / bid for leads software feature on our site

Hello, We are testing the feasibility of installing auction / bid software for service providers in the US (selling and buying services leads, not physical goods like eBay). Background: service providers (mortgage, lawyers, insurance) can only provide limited services to their clients. They need to be specialized to provide quality services and they are often limited by state law on the scope of the services they sell (=they can only sell in the state they are based in). So, on one side, you have providers A who have solid leads (their existing clients, and they care very much about them). On the other side you have providers B who need to buy good leads to grow their business. It is obvious that a provider A could buy leads from provider B, in other words a buyer could become a seller (and should happen often, unlike eBay). Provider A will sell the lead to the highest bidder B, BUT Provider A wants to make sure provider B is ranked very high for their skills and their service. A does not want to lose their existing business because they sold to a highest bidder who ends up damaging their credibility. B wants to buy the lead from a highly ranked provider A because that means that A only has solid leads and B is willing to pay a premium for that. The goal is not to build something from scratch, but to have something up and running fairly quickly and measure/test and learn before expanding. Please respond and explain what other auction/bid software you have deployed, what are your top choices (we prefer open source, and there are several options, with premium features we could buy down the road). Thank you, JB