I'm also assuming you mean $750/mo net, not gross.  

So yes I pretty much went on the google search bar and typed in some typical phrases like “Passive Income Ideas” and ended up trying several such network marketing, monetizing blogs, thinking of a youtube channel to create, affiliate marketing w/ Amazon, and several other ideas that didn’t really catch my interest or attention span.

I can understand both sides of the issue.Now, you gave a property tgat will take some serious unraveling for any seller to monetize.

You kind of got a good idea on how to make Monet and how to look at yourself with regards to what to do.  

Here is where I need your input: In previous mailing campaigns is there a way to monetize these "returned" letters?

So now I am at gross income of $2185/mo - expenses of ($1315 + $350)  $1665 = $520/mo net cashflow!

VERY detailed, line item (with line costs) bids included with the contract, how change orders are agreed to and authorized, things of that nature can help you monetize progress in the event they slack off and get let go, but can also help protect you from bogus contractor liens (read: extortion, to my way of thinking).

How can you monetize them? 

Get the system going from start to end and start monetizing leads.  

Keep your mind open to monetizing all of your rentals assets - not just the inside of the structure.Best to you.