Admittedly I am not all that familiar with Universal's dining plan. However, about a year ago, we were buying lunch at Three Broomsticks and the CM taking our order suggested the dining plan because it would be the same cost and we'd have two drink credits remaining to use at any point during the rest of our trip. So we went with it. I believe I ordered the fish and chips with a butterbeer and DH ordered the turkey leg with a butterbeer. The butterbeers counted as snack credits rather than drink credits. So, you can buy it on a case by case basis when your purchase makes sense for it.