Also if you are able to negotiate this deal please be careful and be sure the current homeowner is applying the rent payments towards the mortgage payments. I would even ask if I could make the payments directly to the lender... If the rent is 1200 and the mortgage is 700 ask if you could sent the $700 to the lender and the difference to the landlord/homeowners... It doesn't hurt be smart.
I advise all future homeowner looking to owner finance aka lease with an option to try this because there are too many homeowners on the verge of foreclosure who rent their homes to keep a deposit and montlhy payments....
As for rentals look on craigs list or check into there local newspaper on line. Keep in mind rent is going up do to the failing housing market. It may be possaible to buy something loer end and pay about the same monthly. Good Luck and i am here to answer any questions you have.