We always go to Sams. If you take 535 from the Disney area, turn left on 192. It's just a little bit up on the left. It's about a ten minute drive from Vistana.
Sometimes they also have the cheapest gas, though the last couple of times we were there it was the same or cheaper at BP.
They definitely have the best prices on milk, but sometimes run out over the weekend.
If you're a drinker, they also have a liquor store.
Sheila