A whole lot of.....
Do you know Scrap?
It is one of those San Francisco gems that once you find out about you wonder how you ever got along without it. It is a treasure trove of reusable supplies for any possible art project that you can dream of.
The way it works: you gather as much as you can, take it up to the counter and whoever is lucky enough to be at the register, gives you a price. And then you pay, in cash. Don't try to barter - you'll just get a frown. I have never felt that my pile of loot was overpriced, not even in the slightest.
Three lessons I have learned:
1. Go with a project in mind - or else you will end up in craft supply overload and buy too much or nothing at all.
2. Don't go with your cleverly crafty toddler - this is not a place for little hands if you don't want to be saying "No don't touch that everyone 30 seconds!
3. Give yourself time - especially if its your first time. There is so much to look at, that being on a time limitation may squelch your creative juices!
Other than that, go and explore!