If you have the time and equipment then yes, do it yourself.
I built my 2-1/2 inch duals from one of the kits that Summit sells. Its basically just a bunch of bends and straights that you can cut up and use to make pretty much any angle. I think the kit was $160 without mufflers, and time to do it. Still I was $$$ ahead over what most local shops wanted to do the job.
It turned out really well and works just fine. Being that I have a V8, I ran them out and under the frame rail just behind the front spring perches. They can't get hit there and look fine too.
I'll try to post up some pics later on.
"Free advice is worth what you pay for it."™