I paid about $400 for my dual exhaust, which also includes two Magnaflow mufflers. I've been running the setup for about 3 years and am very happy. I've heard a few complaints about some of the exhaust kits that the vendors sell, but I have no personal experience with them so it is only hearsay.
As far as routing goes, mine exits behind the tires angled to the corners and slightly down. I've heard that this is the best setup as it keeps fumes out of the cab, and I don't have any fume problems on my truck so it seems to work. There have been many posts complaining of fumes with exhasts that exit straight out he back or in front of the rear tires. My bronco is smelly enough without worrying about exhaust fumes. ;D