I'm sure this isn't what you want to hear, but if your credit is compromised, any financial options you have available to you at this stage will be preditorial in their nature and designed to exploit your situation.
Sort of the same principal as the used car salesman who sells the same car four times, the investor offering owner financing is usually attempting to increase his short term gains over that of a traditional rental.
Furthermore, with owner financing, you don't receive the benefit that your on-time monthly payment is assisting in the repair of your credit, for it's not reported to the credit bureaus.
When it's said and done, your inexpensive home will be anything but.
Improve your scores or save your pennies and pay cash. It's your best bet.