While it's always possible that there is a landlord out there who will take greater risks, most landlords are looking for indicators that their tenants will pay promptly and take good care of the property. You are looking for the minority in the landlord group. Possible, but difficult.
Terms for contracts result from the negotiated agreement between the parties. Sometimes, a landlord will ask for a monthly payment above market value for the commitment to sell. Sometimes a landlord will allocate a small portion of the monthly payment toward the down payment. Be careful here, since a lender might not count those credits toward your down payment when calculating the required down payment you need to make in order for them to grant the loan. Not all rent to own contracts include a component that credit a portion of the monthly payment to the down payment.,
Each rent to own is different. Some are scams. Others are not. It's a very small segment of the market. While you might find one through a real estate agent, be prepared to look on your own also. Choose an attorney who specializes in real estate.