Down payment for owner finance deal

[Michael Lerch]

I have a seller willing to do a seller finance deal on a property they own free and clear. They won't sell it for less than what they put into it around 80k. Seller is open to seller financing but wants a down payment. but unsure how much. This would be a buy and hold.

Purchase Price: $80k
Market rent 1000/mo
15 years and refinance
payments at $400-$500/mo to seller
no idea how much interest or down payment.

Suggestions? I know little to no down payment is preferable :)
 Obviously my first seller finance deal.