GO LOCAL! thrift stores (benefiting the charity of your choice, or not...) local boutiques, yard sales, consignment stores(buy/sell/trade), etc... don't feed the corporation, build on the underground!
DIYer's
live journal has a lot of people that sell their stuffs too, search them! you might find something REALLY cool for one hell of a price!
Supplies
if you can't find what you're looking for elsewhere :/

.A DIY Resource.
bravenet.com