Starting out and could use some advice

[Kennedy Durham]

Hello, I'm in the Sumter area and have been looking to get into rental investing  for a while now. I have an opportunity that has came up and I'm needing help determining if I have a good deal or not.

little background, my neighbor needs to sell his house and move to a place with higher elevation (medical reasons). He wants to sell his house and after talking with him he said I can purchase it for $120,000. 

I'm not sure how to look up the value of his house to see if it's a good deal or not. All I have to go off of is zillow etc... which shows it for $58,000. Of course the zillow appraisal is super old. 

his house come with 3 lots, total 2.5 acres, and an inlaw suite. One benifit i found is I already own the neighboring 1.2 acres. 

I'm curious how can I find out if it's a good deal, and how can I determine the rent? All the houses in this neighborhood are owned, theres no H.O.A to stop us from renting it out I'm just not sure how to determine what I can rent it for.