I dont think there are many axle-back systems that exist anymore. COBB and Perrin discontinued theirs. There's AVO, which I run and love them to death, but I got them used and they're pricey when new. Keep your eyes peeled in the Members Classifieds.
If buying new, you're better off buying a pair of universal mufflers from Magnaflow and getting an exhaust shop to weld them on if cost is a concern and you just want some noise.