Just got an offer and buyer wants me to do Seller Finance

[Shilpa Shankar Bhatia]

Hi there, 

I recently did a flip in Class D neighborhood, and listed it for sale. We haven't got much traction or interest from buyers in past 50 days. However today my realtor got a text from a buyer willing to make an offer asking for a seller carry back with 5-10% down, will pay full asking price with interest. 

I'm not sure how to respond or who can help me structure this deal. I do have a RE attorney.

What is a fair interest rate, how do I calculate closing costs, how best to protect myself and structure this deal.  

Any tips?

Thanks in advance for guiding me.. love learning something new everyday