Where can I buy a high quality South Park cosplay jacket?

I really want to cosplay Kyle Broflovski from South Park. I'm perfectly capable of finding good pants and shoes, and I know where to get both a hat and a wig - but I'm completely incapable of finding a jacket. I can't sew at all, and I don't know anyone who can, so I would really like to just buy one. Without that jacket the cosplay is pretty much incomplete, so there's no way around it.