I never met him but we spoke often throughout the project, I received a fair price for the job and the job was done on time.

There have been multiple times when I didn't offer on a property because I thought my offer would be too low, only to meet the person who eventually bought it for less than I was going to offer.Over the years, when struggling to afford a decent investment, I've come back to condos time and again because they can be high quality homes in nice neighborhoods, and at an affordable price. 

They may be tolerating a lot of bad tenants. 3% should not be used as a gauge to their quality as a PM.

If he is simply sending a bill and threatening action, he wouldn't receive a response from me, other than my lawyers contact information. 

If the owner can wait for the cash-out, he could become your lender and receive monthly payments until you do a ballon in a few years. 

Think BIG.In my experience and opinion, and you will receive a ton in the days and weeks to come, commercial multifamily is the way to go, especially based on your $15K/month goal. 

That is, if they're charging you less than the IRS minimum, the IRS will require them to calculate interest based on the minimum rate and pay tax on that amount even if the interest they receive is less. 

I’m looking for quality products at affordable prices that are better than the big box store lines.

Quality over quantity my friend.

At the end of the day, I'd say use the capital in your house now with the hope of receiving income at a later time.Hope this helps.