What's my house woth?

[Curran D Bishop]

I have a property in Carbondale, IL which I bought in 2013 for $89k. I've been renting it out to a friend since 2018, and would like to sell it to him. He's new to home ownership (this would be his first house purchase). I want to give him a fair deal (I don't want to take advantage of him neither do I want to give him the property), but I'm not sure how to evaluate the value. Zillow says it's worth $90k. Carbondale is not a "hot" location, but I'm surprised it's only appreciated a little over 1% in the last 8 years... what tools do you use for running your own comps?