I've come to learn that they have about 15-20k in appreciation that they want to take advantage of in order to pay off some credit card debt.

I've recently talked to about a dozen local banks and credit unions, and it was difficult to find one that offered a LOC on an investment property. 

My understanding is that if I attempt to put a property under contract, I would need to essentially put down a small fee (varying) in order to show that I am serious.

For extra credit, you should refer them to a great listing agent and make the introduction!

But alive and well many places such as banks, credit unions, etc and it does not benefit the consumer overall. 

I don't have very good credit, but recently I sold my house and have a little over 200k in the bank. 

A real fixer in an area like that might be cheap enough for you to buy in cash and then use whatever short term credit lines you have available to complete the rehab.

Keep in mind in my case I have an 800 credit score, two rentals, and a primary home if that changes anything from the banks point of view.

you can, you would have to pay back the mortgage company the money that was borrowed. reverse mortgage is a lien on the property for the money that was used. almost like a home equity line of credit.

To do well in real estate you need money, credit and a good team (agent, property manager, contractor etc)