Question about rental rate discrepancies

[Matthew Patton]

Hey all,

Coming here to pick your brains on this rental rate researching.

I have been analyzing like a mad man. To get rental rates for an area I am using the BP Property Insights tool, Rentometer, and then will look whats actually being advertised for rent on Zillow. On zillow I will filter out what isn't comparable to what I'm trying to actually rent out. So for example, I will only look at 3/2 SFHs. Then I'll look at 5-10 of them and figure out a range. 

There is an off market home through family that I have the opportunity of buying. I'm trying to get a good gauge of rent. 

BP Insights suggests a rent of $1855 with a medium confidence and a range of $1446-$2404.

Rentometer suggests a median of $1800 with a range of $1600-$2000

What's actually currently being advertised on Zillow, when specifically looking at 3/2 SFHs, gives me a range of $2450-$4100 based on taking about 10 homes and figuring out the rent per sqft. This, of course, flies in the face of Rentometer and BP Property Insights. 

If it really does rent for even $2400, it'll be a 12.5% COCROI. It's in a good neighborhood and a good school zone. Family is moving out because they are getting relocated down south. They are willing to sell it to me for what they paid for it a year ago ($251k) and has a new roof. It's worth about $275k now. 

The only thing making me hesitate is the disparity of the rental rates. 

Any insights?

Thank you again!