Let's assume your house is worth $500,000. The option price might be $5,000 and the monthly might be $1,750 or so. A lot depends on the home's location, the schools, and other factors. But that's a ballpark.
But know that your are renting it and not selling it. More than half of the Lease Purchase contracts don't close, according to some statistics I have read.
1) If the market goes down in the next couple of years, and it may, the buyer will not want to buy it at today's prices, even if they have agreed to do so.
2) The mortgage criteria is not likely to improve to the point where someone who can't get a mortgage today, can get one in six months or a year. So if they can't get a mortgage now, why will they be able to get one later? Know that answer.
If they have a great credit score, but need more of a downpayment, often the monthly amount is increased over market rent, so as to give them a credit against the price or a downpayment buildup.
The bigger question is why would you want to risk selling it next year for less than you can today?