I run a Dynomax Ultra flow SS system. Its just right as far as tone and sound level goes. Was 187.00 on Amazon. They did discontinue this kit though. The Super Turbo system is available still. Stay away from Gibson. Its garbage. I got suckered into buying one 5 years ago and in October 2011 it finally fell off. Muffler fell off the truck while driving. Rusted from inside out. "Best 380.00" I ever spent. I went right back to Dynomax.
Flowmaster sounds good on the right application. V6's are not the greatest sounding with the wrong muffler. There is a 3.0l ranger here that has a Borla and its expensive but sounds great. MBRP makes a couple, but the price for the axle dump kit is still 250.00+, MBRP sounds amazing too.
Unless you do your own or have a shop do it, I think the Dynomax is the cheapest cat back kit out for now. Last I checked anyways.