Review my Startup: help me critique/improve/iterate my startup

Grosper.com is a group buying website for user initiated deals. We concentrate on big ticket items such homes and wheels. We allow an individual user to 'Make a Demand' to rent a home. Once enough users are interested, we contact landlord that own buildings and ask them for the best price for a group (min. 3). Landlords have been willing to give at minimum 15% discount up until now.<p>I would like to discuss how we could automate the process to ensure that we don;t have to spend a huge amount of time always going back and forth with the landlord. Also, how could we decrease the time to form the group and then list a deal for the group?