My mortgage broker thinks I should do this ( he is also a friend). 

I'm guessing that you are an RE Agent/Broker. 

Finding something in our budget is tough...the mortgage broker can approve us for about $275,000 so rehab and purchase.  

He listed it for sale 3 years later and the broker suggested a price of $300,000.

I highly recommend that you use Redfin in tandem with Zillow to gauge property values as Redfin is a broker with MLS access and they update their property feeds every 15 minutes or so.

if you paid for appraisal a year ago you should have some relationship going on there, so feel free to ask.Another option is to talk to 2-3 local brokers and ask for them for Broker opinion. 

Hello,Looking for a broker who knows the Phoenix AZ market to assist me with buying a small commercial property...I am looking at a 20 unit property and need some boots on the ground to represent me.

I am an off-market broker here in Manhattan but I invest outside of the city.

I can't imagine being rated by the server at a restaurant, the checkout person at the hardware store, or anything similar.

I have a similar situation where a broker who is working for an insurance company is looking for rentals for a displaces insurer.