I have a couple ideas as I am doing this search myself and am trying to pinch every penny I can. I am looking at either Banks or Magnaflow so that makes it a little difficult to keep the price down. Here is what I've found so far:
For a complete banks kit I have found no better price than I have here http://performancetruckproducts.com/exhaust-1.html?manufacturer=9
. This is a 2-1 kit that is 3in mandrel bent stainless steel pipe with a 3in straight through muffler to a 6"x5" stainless steel rolled edge tip.
For a true dual Magnaflow kit I looked up part # 11225 on Amazon and got a great price of somewhere around 60-70 dollars a muffler. Then my local shop would run some alumanized pipe for $150. Add in a X pipe I found on ebay for cheap and you have a true dual setup with quality components for less than $400. Of course if you want stainless and mandrel bent pipes that will of course cost you more.
I am leaning toward a 2-1 kit as the way that the exhaust has to route down the truck it just about negates the purpose of having true duals. The pipes from the driver side catalytic converter bends right to the y-pipe on the passenger side then run almost the whole length of the truck down the passenger side then would have to split back to the driver side making essentialy a C shape and negating any real performance gains due to many bends in the pipe restricting airflow. Whereas the 2-1 kit from Banks runs straight back from the Y-pipe and out the back with minimal bends in the pipe.
I just did a quick search and found you could get a Magnaflow part# 12641(30in long) for $108 or 12619(14in long) $75 and have your local shop hang the muffler and run the pipe for you or just cut it in to your factory 3in pipe for ultimate savings. The only difference in the two mufflers I listed is the longer the muffler the more quiet it is. I would go for a 30in muffler but if you want more noise then the 14in would be for you.