For example I would rather buy a property for a $100k discount that may have negative cash flow of $500/mo month for 3 years than pay market value for a property that cash flows $200/mo.

If this is simply you not wanting to accept partial payments and the rent is current, stop accepting it - and send a Lease Violation/Notice of Quit for Non-Payment of Rent - and force the full rent to be paid per the lease or start eviction.  

If you aren’t saving the money up to buy another property chances are nothing will pay a higher rate than paying it towards your mortgage.

if you're W2 and full-time, hourly or salary, you should be able to go off your pay stubs for qualifying.

Otherwise, you could network with a local Realtor to your area and see how many duplexes sell per year within your acceptable driving radius.

I haven't seen any quads in our metro make more than $2k per unit (unless in 78704), let alone $7k, so not sure where those metrics come from.

If I can pay it off in a 7 years I’m fine.

Anyone over 18 fills out has to furnish their social security and driver's license numbers, and pays a fee for a credit / background check.

However, chances of making a mistake or overlooking an opportunity to save are higher when it comes to rentals.The dilemma is whether it's worth paying a professional in this case.

We’ll pay to get it fixed that’s not the problem.