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.