Ask HN: Help me hack my startup's business model

My startup, Grosper.com does group buying for home rentals. The way we make money is by taking commissions from users and landlords for every deal that goes through us. However, in terms of scalability, it is a very labour intensive process and thus, we have been looking at different types of business models that are more web friendly and less labour intensive. I was wondering if the hackers here had any ideas on how we could move away from the commission model to a more self serving and scalable solution.