need new exhaust system

I need to get a new exhaust system as my pipes decided to rust through over the years. I'm on a pretty tight budget and am looking for something that will help out my z. I have a 76 280z with the cat converter. I can get a Nissan exhaust system for $160 but MSA has the "turbo" system for $125 and some guy has been selling Monza exhaust systems on ebay for $137. I only need the pipes past the cat converter and the muffler. Is there anywhere I can find some decent stuff cheaper? And of those and others what do you suggest for a poor kid trying to get his z quiet