Ultimately the market determines retail price and lease payments. You can set your price and lease payment so that your deal makes money but if no one bites then you will have to adjust your numbers to get the deal done. That is the market forces in action. Do your research on nearby similar home prices and give it your best estimate on what those values might be like during the option period of your deal. Likewise research market rents and lease payments on option deals to determine what the market will accept.