only a few companies make a header for tjs. Borla, banks, and a new company just came out with one but I forget the name. It seems that some people have a problem with them cracking sometimes though. They usually seem to cost about the same everywhere which is about $400.
A lot of cheaper headers have thin flanges which have a tendency to warp. If you want it to last, make sure the flange is nice and thick. I've seen el-cheapo headers for a TJ for just under $200.
Ceramic coated headers will keep thier nice shiny finish for a long time. They cost more though....... Edelbrock makes a set that's over $700.
Quadratec and Summit Racing usually have decent prices on headers.
banks makes a good header with thick flanges there a little priceeee but they have a lifetime warranty and look pritty good to all shiny and stuff. get in like petersons or jp magazine and look around there alot of exhaust companies in there with websites.