I ususally get my Quickutz from crazyscraps.com. Their prices are pretty good, although they used to be cheaper! I've also bought Sizzix from JK crafts--I think that's what it's called.
Also, I've bought a lot of pre-cut shapes on Ebay. There are all kinds of sellers who have packs of shapes that I want, but don't want to pay for the actual die. Just watch out for shipping on some of them!
My favorite one is called CMCScrapping. She puts the shapes in little ziplock bags that are labeled and most have little pictures so you can see how to put them together. Oh, and her shipping seems to be one of the cheapest. Here's the link to her store:
http://stores.ebay.com/CMC-Scrapping...Q3amesstQQtZkm