From the seller's point of view, just as you may not be able to afford buying a home, did you consider that they may not be able rent it out for financial reasons? If their mortgage (principal, interest, taxes, insurance) is more than the market rent, it probably would not make sense for them to take a negative hit each month to rent it out.
If you are truly set on home ownership now, expect to pay more than someone who has the finances to buy now. I would recommend that you consult with a local real estate agent to obtain real advice from someone that knows your market. My view and opinion were general views and to gain specific advice, one would have to be licensed in your state and have knowledge of your personal financials.
And you're right--if you approach an owner correctly, eliminate all your competition who are lined up for rentals.
Hope that helps.
Unwavering Commitment to Service
Deborah Rigsbee Miller, Real Estate Broker
Coldwell Banker HPW
Below is a link to Lease purchase homes in Central Alabama