i got mine on ebay, from "boss bearings" for like $20, but "pivot works" and "all balls" makes them too, just to name a few, search ebay, or google them,
or check rockymountainatv.com,bikebandit.com, and unless you have a bearing puller, they're a biotch to get out, ya gotta get a long flat bar, put a little bend on the end, stick it thru from the other side and keep beating the opposite one out, little by little, moving the bar arond it as you go, let em soak over night with some pb blaster or oil to help loosen them, might need some heat applied too??
oh yeah, someone on here posted that they took theres to "napa" and got some for cheaper, there was even a part # listed, do a search on here for "axle bearings"