Hi
If you know the postcode of where you are staying you can do a store search at www.walmart.com. They even sell GEORGE clothes and returns can be made at ASDA.
Another good supermarket is PUBLIX. More like our Sainsbury's, the good thing is you can rush in and then out as they are not massive where as with Wal Mart you are likely to have a good look round and then spend ages in there.
If you are at the south end of International Drive it may be worth going to the Walmart on the Osceola Parkway as it is quieter than the one on Sandlake Road and also is less likely to run out of stock.