should i sell to my tenant? owner financed question

[Robert Hastings]

i purchased last year for 25k from a friend who had a tenant in place.  great tenant.  paying 650 month.  tenant responsible for energy bills.  im responsible for water, insurance and taxes.  i clear 500 per month assuming no repairs needed.  for the past year, no repairs have been needed.  i even have a clause in my lease, repairs under 100 are covered by tenant, over 100 i will cover.  

in any event, she wants to buy it.  she doesnt have good credit and she doesnt have any savings.  but she has an extreme desire to make this place her home and take care of it for her son.  a lender wont touch her.

i told her i would consider something...and this is what i think...im not a numbers guy but tell me if its worth it or should i just keep it and rent.

i bought for 25k off market, the house next door sold for 60k, so 60k would be my price. i think its fair to double or 2.5 times market rate for 100% financing for a 15 year term....

60k at a rate 8% i think i calculated a total pay out roughly of 90k after all payments are made 15 years later.  

her payment is a little less then her rent now, i secure payment for the next 15 years, if she defaults i will get her money and my house back.  deed wont transfer until paid off.  in the contract, i will act as bank, and will not have any financial obligations with regards to taxes, bills, insurance, repairs....im just a bank.

this is just surface conversation, but am i on the right track?  do the numbers sound attractive?  would the numbers and only the numbers make or break your decision?

thanks