Paul: A couple questions for you. Are you using Seller financing because you are unable to get traditional financing? If you haven't exhausted traditional financing I would be willing to set you up with someone to see if you are qualified.
If you have exhausted traditional financing and are unable to obtain it seller financing can be a great way to purchase. The specifics of this particular loan seem to be a reasonable down payment the term is really short and the interest rate is high.
Let me know if I can help in any way.
Harward Real Estate