Family Owner Financing

[Thomas Porter]

Hey all!

I'm pretty new to real estate investing and looking to get a solid start. My wife's grandpa unfortunately just had his leg amputated due to complications of diabetes and therefore they will likely need to sell their home due to stairs. I would like to buy their house as there is the opportunity to convert the basement into a basement apartment. At this time to do that I would need them to agree to owner financing to make the deal work. I have listened to many real estate books and youtube videos, including those on bigger pockets so I know the theory of an owner financing deal, but does anyone have suggestions? 

I had a real estate agent run the comps on the property and he said that it is right around 165K. To make the deal work I need it to be more around 120-130K and I also have to factor in the money needed to convert the basement into an apartment. I want to be fair to my family and obviously, that relationship is more important than getting a good deal, but I figure that saving on realtors and some closing costs should help get the price down. Thoughts?