Correct way to evaluate a 4-plex?

[Austin Davis]

I purchased my first properties off market not too long ago and pretty much made up my own way to evaluate them. Probably not the best decision as a newbie, but I think I did OK. I made a spreadsheet that subtracts my desired cash flow from the NOI to give me a mortgage payment. It then calculates an offer price based on that mortgage payment instead of using the cap rate method.

Since 4-plexes are right on that border of residential and commercial, I wanted to see if I did the correct thing by basing my offer price off of the income of the property or if market value should have played more into the equation.

I got excited to buy the first time, but I will reach out for help BEFORE next time.  Thanks, everyone!