You'll notice that most Santa costumes come without gloves. You can find inexpensive white gloves in many styles. Here's some examples. (The images are clickable.)
Marching band gloves can also do the trick for a very low cost:
TheCrownStore.com
The Bandroom
Peacock's Marching World
If there's no time to order online before Santa's visit, you may want to check out your local marching band supply store. Marine dress uniform gloves also make great Santa gloves, but are somewhat expensive.
As noted earlier, most Santa costumes come without a beard, mustache or wig. One of the best deals we've seen combines a Santa hat with a wig, beard, mustache and even glasses!

Purchasing a beard and mustache by themselves can get expensive, but these are downright cheap:
Frank Bee Costumes
Magic
Makers
You can temporarily turn your hair white with a hair coloring spray. Use this in a well-ventilated room!
Depending on which route you choose, there are other Santa accessories that you might want to include:
To attach fake eyebrows (and some beards), you'll need spirit gum.
You can use a pillow for your Santa belly, but they tend to shift and cause discomfort. You might prefer a costume belly, which is worn like a tuxedo vest to keep it in place.
Go
To Chapter 3: Make Your Own Santa Suit