What immediately occurs to me (and I apologize if it's been asked already) is that you likely have to offer slightly below market prices to be able to make a decent profit and mitigate the risks. So someone in a neighborhood with a better than average home will not be enticed by the lower price and will likely sell through conventional means. Someone with a below average fixer-upper, will see the price as very attractive and sell through you. So anything that's just predicated on expecting homes listed on your service to be centered around the average value will not work. How do you account for this sort of thing if you don't see the house?

Also in a forclosure situation the owner needs to make a quick sale - your service would look very attractive (a killer niche of the market for you guys.)