People have posted that you can buy a 6 pack of beer cheaper than one serving at the resort gift shop - as opposed to the resort pool, same for DTD. I brought wine, and did a grocery stop and bought beer for our room, no problems. I also bought a bottle of wine at the gift store for under $10, and the CM uncorked the wine no charge!
Also, do know that at the parks (like Epcot, or MGM, Fantasmic) you can only buy one beer at a time - so while dh and dd were saving our seats, I could only purchase one beer, and then go stand in line again!! (of course I was lucky when a person behind me wasnt going to purchase beer and ordered one and I bought it from her!!)