$726 is probably a decent price for a set of good quality headers. I'm not sure on the quality from these guys, i've never dealt with them. However i believe these would be a low volume possibly even hand assembled part. I have hand built headers from scratch for high end race cars that took a few days just to make the jig to assemble them on. I also sometimes look at a given item and think man those are expensive, in the cases where i can relate to i can see the costs involved and think that is a decent price. How much would you want for a set of headers if you were trying to sell them?