They're pretty decent quality too! I bought a design a friend did and I'm pretty impressed with how fast they shipped.
They seem to have a "buy six get everything 50% off" thing so all the stuff I just uploaded is also perfect for that.
ALSO it's so easy to set up your own storefront and they charge you nothing up front. Unfortunately, each sale only nets you a percentage, as they have to get the money for manufacturing and whatnot somehow. I think I make 22 cents per sticker sale. :'D