I got mine from bigbunny but I've seen them on ebay. Originals are a nylon bush but the ones on ebay are brass.
In fairness Bigbunny fitted mine but it was just a few minutes and it was done. Pretty sure it's what the pedal pivots on, theres a pin that goes theough it and I think the pin is held in place with an "R" clip or something. There have been several threads about this so may be some pictures.
Tip:- if you fit the brass type smear a little grease or copper slip on it.