Mortgage bankers and brokers now have a single place to transact business: LendingGear.com. The Web site allows brokers to post loan scenarios, which lenders can then bid on. The privately held auction portal is just a few weeks old, but it is already paying off for the firm’s two owners. Marriage of Necessity. One day a wholesale mortgage banker met a retail mortgage broker and knew it was much more than a hunch that they should develop a Web site for the entire family of bankers and brokers...