The most difficult task related to placing a CAP rate on a property is you need the TRUE CAP RATE so you can compare apples to apples.

Typed on an iPhone 

I don’t know your area prices but in my experience here in CA, that is a bit on the high side and I would expect other bids to come in lower.Best bet is to get at least 2 more bids, make sure they are apples to apples, and get their timelines and warranty info, those are just as important as the price as time is money.

I've found its just an easy way to qualify a property on an apples to apples comparison.

I was not able to find any duplexes that sold in the last 6 months in that area to be able to do an apples to apples comparison. 

Finding 3-4 companies per trade and evaluating proposals to make sure they have our project specs and are apples to apples comparisons. 

A few bad apples can spoil it for everyone.https://www.wired.co.uk/articl...

You can still buy a brand new home 30 minutes from downtown or 15 min from Apple, Amazon, or Tesla upcoming properties for well under $300K.  

@Andrew Mok the problem is that your three options all have different goals so it is like comparing apples and oranges. 

Check out Apple, they are one of the most cash-rich companies in the world.