I was wondering the same thing!
I paid like $275 for mine from Subaru Lachute.....its resonated, Otherwise, a non-resonated one is like $175 (those prices are in CAD$). Its not just straight, theres a bit of a bend in it....but, I guess you can get one made at a muffler shop...just weld on 2 flanges to a straight pipe. Hmmmmm....