I don’t think it’s any different from “buying from one and renting to another”. However if the seller wants to include the lease as part of the conditions, because of bad credit or debt, you need to be very careful. You could end up with a deadbeat and have to evict later. You should still qualify him/her no different from any other applicant (credit report, income etc.). The amount of price concession should be based on the risk you have to take in case the qualification was bad.