There is Publix grocery store pretty close to the south gate just off of Hwy 192. It's at
Xentury City Center
2925 International Dr
Kissimmee, FL 34746-4407
Main: (407) 397-1171
Not all Publix carry liquor however, call first. There is Goodies (not Goodings) near the Publix, but they can be expensive. It's a large convenience store.
Someone said Hess gas stations are cheap. There is one at Downtown disney. You have to cross the street but it is close enough to walk to from Downtown Disney and the Disney hotel shuttle bus. I wonder if Hess stations on Disney property are cheap also? Their gas is.
Some people go to Goodings at Crossroads. They make up for the higher cost by skipping the taxi. They take a hotel shuttle to a downtown Disney hotel, Doubletree Lake Buena Vista is the closest, and then walk the half mile or so accross Hwy 535 to the Goodings in the Crossroads shopping center. It saves cash but uses up time.