[ridextreme]

It's just that I submit a few deals to a lender with really really good rates and no fees.
However the commission is so low that sometimes it not worth my time.

don't let the merchants close you on a "good rate" you should be closing them on why they're getting a high rate. If they qualified for such a good rate why aren't they going to a bank?

To answer your question you can't just make up a fee sheet and add it to the contract. It needs to be specifically drawn up by a lawyer and processed through a reputable processing company.