Great boil down of the RedFin model. Excellent marketing. Note, for those curious on more details around RedFin ... I did a writeup of RedFin here based on detail notes from a Scoble interview of them in 03/07 (and included a link back to this as it was the best explanation I saw of the model).

http://timbauer.bauerfive.com/2008/04/18/redfin-making-more-with-less-po...

Again, great work. If you want, you might email me around the ballpark costs for such a segment. I have a similar business model to RedFin and something like this could really help.