Yay, I'm so glad there's a thread about this!
Oh, and PLEASE post pictures of your costumes, guys! I go browsing around this site and other sites looking for South Park cosplays (usually to waste time and avoid doing important things like work and school). But there are only a handful of South Park cosplays---about 5 minutes worth if I click on each picture---which means I have to return to work/school a LOT sooner than I'd like to!
I'm going to make Stan and perhaps Butters for a friend in the hopes that we go to Comic Con next year. (I'll have plenty of time to finish....right?)