$1000!! That's way too much for a full exhaust.

You can buy a full kit for ~$700. But maybe you were including the price of headers... even then, it seems a little high. True duals from a shop should cost you around $500 (including install) and the headers are less than $300...
Regardless, I don't think that is your best route. First off, our stock headers are quite good already, since they are shorty headers and not a manifold. The only improvement from there would be long tube headers. So, you would be paying for BBK's name and a shiny coat - that's it.
And unfortunately, the magnaflow exhaust you listed is only the back half of the set-up: it's a catback system (which means it comes after the mid-pipe) that is designed to work with your stock Y-pipe (mid-pipe).
If you want a full exhaust, I recommend 3 ways:
1) buy a full kit (crossover mid-pipe w/cats for emissions, mufflers, tailpipes) that's made for your stock (shorty) headers. Pypes is the only company I know that offers that...
2) get an H-pipe adapter (cut your stock Y-pipe right after the cats and it attaches there) or an H-pipe replacement (replaces the stock Y-pipe) that works with any GT catback exhaust. AM (American Muscle), MAC performance, and others have these.
3) have a local shop make you a true dual exhaust (each side has it's own separate "straight" pipe that goes to the muffler) with mufflers of your choice. The mufflers will cost you $50-100 apiece, and the shop should charge you around $300-400 (I think) for install.
Of course, there are still other options: long-tube headers, off-road (no cats) midpipes, exhaust cut-outs, etc. So maybe tell us more what you want (noise, performance, appearance) and what restrictions you have (emissions/inspection, $$$, ground clearance from a lowered car or lots of speed-bumps) and we can guide you a little better. But those options should get ya started.
