The other Orlando business that delivers groceries is WeGoShop (
http://www.wegoshop.com/location/wgs-location15.htm )
I have never used either service, but for a number of years, both companies have gotten good reviews over on the DIS DVC boards.
If I'm not mistaken, the differences between the two are as follows:
Garden Grocer has a set list of items and prices. You select specified items online, they go buy them, and add a small service charge to their established prices (which apparently include a small markup).
WeGoShop will shop anywhere you want -- including Costco, Super
WalMart, and other discount places. You specify what you want, including brands and package sizes if that's important to you, and they go get it. They bring your groceries, with the receipt showing what they actually paid for your stuff, and they add a service charge. Like Garden Grocer, the service charge is small and specified ahead of time.
I would check both and see which fits your needs best.
The other thing to check is to be sure your resort has the capability to accept food items on your behalf if you are not there. The DVC resorts have the ability to store refrigerated items, but check with your resort to be sure they can accommodate that. The grocery services probably know, but I'd double-check with your resort to be sure.