Have you discussed this issue with him? I wouldn't kick him to the curb just yet, but I'd tell him it bothers you. Is there a reason he has to be so cheap? Is his income such that he can't splurge on soft drinks.....and heat? I think he's being cheap, not just frugal. If he doesn't change his ways a bit, I'd move on. You are at an age where you should be enjoying every bit of life and not worrying about a 1.50 soft drink!
At his age i do not think that he will change, it sounds like he wants you to pay for it, can he afford to go out or, is this his way of being frugal, if he has the money, and will not spend it on you get rid of him, and i would tell him to loosen up, that when one plays they have to pay he sounds like a typical tightwad , and that if he does not feel you are worth a little better treatment , that he needs to stay home by himself luck jo