exhaust kaput

[dungbtle]

aloha,that other day i smelled exhaust fumes when i opened my driver's door, so i bent over and saw there's a small leakage on my exhaust pipings before the center box, so i went to have it welded up . just yesterday, for the fun of it, i tried to be sensitive and heard some exhaust sounds coming from the side of the car... so i bent over again. and this time saw a one inch slit on my center box. i think the whole of my exhaust is populated with rust. its giving new holes every now and then and i'd have to replace it already.besides i dont like the muffler i'm currently using. question is, i know nothing at all about exhausts.pls educate me, are there alot of selections of exhausts? besides our beemer types? what about japanese exhausts? do they fit our cars?and are they more effiecient and cheaper?(e30 2door) where can i get them and what is the approximate price i'd be expected to pay? what about second hand ?i think my whole exhaust has to go. hopefully i get my bonus soon!