You are not financing anything at 3%, you are paying a 3% convivence fee to get your money. If you pay your credit card off, you already have the money. If you pay interest on your credit card (stop using it to gamble!!!) then you are at much more than 3%.
It would be like saying it costs you 3% to apply for the mortgage and then you pay their rates (on the amount including your 3%).
Otherwise, I agree with your statement that the 3% is fair.