2.25 isn't usually that expensive, any muffler shop should be able to do it.
It'll cost around $200 - $300 for just the piping, if you add in the flex-pipe its another $100, if you don't supply a muffler it'll be another $100.
So figure $400 - $500 with flex-pipe and muffler.
The problem is finding a muffler place that will do your exhaust without putting a catalytic converter, ask around if any of your friends knows someone that works at a muffler shop....