Greddy over priced? hahaha, Maybe in the honda world but that's only because half the shit made for hondas is total junk.
My y pipe back exhaust was pretty cheap at $700-800 if you want a true cat back exhaust add another 500 either for a Y pipe or a full cat back exhaust.
Also the exhaust I ran on my civic was around $1400.00
Greddy cost too much? hardly.
Exhaust are the small items they sell, the big stuff is turbos, turbo kits, intercoolers, and that crap they call a piggy back ECU