Hey man, you have a couple options. In the 'Burgh, there's South Hills Brewing Supply. They have 3 locations: Monroeville, North Hills, and Greentree. I prefer the Greentree shop, seems to have more inventory to chose from.
There is supposedly a True Value hardware store in Bellfonte that has brew supplies. I personally go to Bootleggers in Altoona(if you can make his hours) or Brew-It-Yourself in Loretto. In a pinch, I'll stop by Oak Spring Winery just off I99, Pine Croft exit.
I've only been to BIY once, but I think it's going to be my favorite. Talk to Ed, he'll hook you up. Plan to spend some time, he is a veritable fountain of knowledge. My brother-in-law swears by him.
I find it hard to believe there aren't any shops in SC. You'd think a college town would be a prime market.
Hope this helps.