Hi Heidi -
The Walt Disney World
gift shops are incredibly well stocked with nearly any personal care item you may have chosen not to pack (or forgotten to pack). On more than one occasion I've been grateful to have been able to run down to the shop to buy a replacement for the toothbrush that didn't make it into my suitcase. That being said, the sundries in the shops are priced at a bit of a premium. Prices and change and may vary by brand, but for example, a travel size deodorant is likely to be about $3.95, a travel toothpaste about $2.95, travel shaving cream about $3.95. Basically you could budget about 1.5 to 2 times what you'd pay at your local Target.
In addition the gift shops, you can also get full-sized personal care items from several local delivery services. GardenGrocer.com will deliver almost any supermarket item. There are minimums and deliver fees, but if you also want beverages and snacks, this could be a good choice. Also turnerdrug.com will deliver most drugstore items to the Disney hotels. If you need several full-size personal care items, but not any groceries, this is probably your best bet.
Good luck with your planning. Please let us know what else we can do to help.