I participate in some charity giving.

@Maria Amaro this sounds like a personal matter for the buyers and you aren‘t runnIng a charIty.

The GC isn't running a charity and neither should you be.So if you told them or had a contract with them to do it at cost (without any stipulation as to what cost truly is) you would probably be able to argue that you should get the actual true expenses plus some admin fees and your time on the job without profit. 

You're not a charity, you're running a business.

Put the property in a trust for the benefit of a charity.

Maybe pick a charity in your area and give the money to them in your referral's name.  

Quick suggestion here would be to make them tangentially related to income- for example you want to give 5,000$ to a charity of your choice.

We have since grown our meet up to about 40-50 people on a monthly basis, paid sponsors, and charge $20 at the door, which we DONATE to a local charity!

I do not want to fall behind market rents, I want to contribute to setting market rents and I do not want to turn my business into a charity by supplementing tenants rent.

There are charities out there to help people down on their luck and you're not one of them and if you pretend to be, you'll be down on your luck yourself and you can bet your ***, the bank isn't going to care about your sob story.Not Signing A LeaseMaybe they're a family friend, a family member, or you looked the guy in the eye, shook his hand, and you just knew he could be trusted at his word.