Well, you can buy them at any smoking store. That's what they're for after all! ;-) Go to a cigarette store or one of those glass shops all the young folks go to (where they sell smoking utensils).

This is an interesting idea... I don't think I'd actually use a pipe cleaner for anything permanent or dependable but I'd use them to clean areas that otherwise would be difficult to reach. Being able to mold those guys into different shapes certainly makes them extra-useful. Thanks!