I got my exhaust wrap at CheckerAuto in American Fork... It cost me ~$50 do get everything I needed to have enough to do my header. (I bought a 50(linear)'x1" roll, and had 2 linear feet left. I bought stainless steel "zip-Ties" (these are incredibly strong and will not let go!)
Before I wrapped it I did the "Ceramic Coating" in a can, and had it baked on per instruction on the can, and it came out very nice and only cost me $7, but that was on a header and it might not be feasable to you to do your whole exhaust under your body panels..
I also bought a can of "Silicone Spray" that goes over the wrapping when its all finished, and then gets baked on (take it to a local powdercoater and use their baking oven). If you don't use the silicone spray, then the exhaust wrapping will soak up water, and retain it. Therefore causing rusting issues underneath the wrapping. However this is very effective.
Heat shields will keep the heat off the floor panel, but imo its more of a pain to work with.
*Picture is just after I completed the exhaust wrap, before the silicone spray.
Here is a Write-Up Article that I did last year on my process... may or may not help you.
http://articles.jeepforum.com/Reduce_Underhood_Temps-_Exhaust_Wrap/