Here's an alternative I've used in the past:
Assuming you are flying into Orlando, there is an Albertson's that will shop for you at no charge. It's right on the way (417) to Disney from the Airport.
I've faxed them a shopping list with my flight information. When I arrived at Albertson's, I go to customer service and they wheel out a cart from their walk-in cooler. Everything is already scanned and bagged. You just need to pay the total amount.
Here is the contact information for the store:
Store Number 4462
Store Name S. Orange Blossom Trail and Deerfield
Address 12981 S. Orange Blossom Trail
City Orlando
State FL
Postal Code 32837
Phone (407) 857-5666
FAX (407) 857-0132
Store Hours 6 a.m. till 1 a.m. 7 days a week
It's been a couple of years since I've used them, so you might want to check if they still do this.
I've also had great success with wegoshop.com. It's really more of a personal shopping service. Marge owns the local franchise and she's really spectacular.
But there is a charge for delivery. If you just need a few things, it could be expensive.