I talked things over with my mom and with hrafn, and I decided to go for it. I called the guy back, and we're all set. I'm going to come up with a lease-thing and email it to him for additions/revisions, we'll both sign it. He'll get me a check for 1/2 of August and all of September and move in on Saturday, August 16th.
Big change, but I think it will work.