Rent to own homes are pretty rare these days. They used to be more common when we were in a strong buyer's market (more sellers than buyers) and sellers would offer rent to own as an option to attract more buyers. However, most parts of the country are now in a very strong sellers market. Sellers want to sell, not rent to someone who may or may not qualify down the road.
Plus, rent to own is never a good option for a buyer. You're typically paying a higher rent, and that money may or may not be going toward your down payment. Plus what happens if you get to the end of your lease, and you still can't qualify? The seller can just keep your money. Why not use this extra money you plan on spending and put it toward paying down or paying off your debts?
I assume you're asking about rent to own because you can't qualify for a regular mortgage (due to credit issues)? You need to figure out what is keeping you from buying now, and fix those issues so you can qualify for a traditional mortgage down the road. Good luck!