To save some cash, get mild steel. If you found a muffler second hand, you can get away a catback knocked up for less than $500 including the price of a second hand muffler ($100-$200). I have always had mild steel, and to the naysayers who say it doesn't last as long as stainless or it's shite, you wont own the car long enough, plus i reckon mild steel sounds better.
That doesn't sound to bad, but I sort of see it as though I'd be half doing the job because in the long run I'd want a complete stainless set up.
I might go have a chat with the local muffler shop and see what they think about the x-force one (I found a 2.25 http://www.ebay.com....984.m1423.l2649)
I was quoted about 350 by them for a magnaflow + labour and tip I think