How Would You Determine Current Market Value on this House?

[Tim Porsche]

Hey All, was approached by a seller earlier this week and I have an opportunity to buy a SFH rental at a discount. I'm having a tough time determining what the current value of this house is though and would love to hear some opinions and would appreciate any feedback.

The primary reason I'm having trouble determining what the current value would be is because on one hand the house was appraised last year at $148,000 by an appraiser according to the current owner. However, I see on Zillow that it was listed for sale at $135,000 back on 10/2017. I asked the seller about this and he said he originally purchased the house for $60,000 and rehabbed it with the intent to keep it as a rental. When the last tenants moved out, he was unsure if he wanted to sell or rerent it so he just put it on the market for sale for about a month, at which time he found new tenants and decided to keep it.

He said the reason he looking to sell at a discount now is because he has two flip projects on the market that haven't sold as quickly as he had planned and he needs cash. Also, he doesn't want to kick the current tenants out as they've been very good. I know this area relatively well...I have a rental just about a mile away from this one actually, and would estimate the value at $140,000 conservatively after viewing the inside and outside today. Should I be worried that it was listed for sale at $135,000 for a month and didn't sell though? Or am I overthinking this? He said he'd be willing to sell for $120,000 but is open to lower offers. I looked at comps in the area and it looks like it should fetch $135,000 - $145,000 all day. Is there anything else I should be doing as due diligence before making an offer, and anything else I should be doing to make sure I'm valuing this correctly? Thanks in advance for any advise.