I just replaced my 2004 TJ Wrangler cat. I paid extra for the Walker product at car-stuff.com ($420) because it is a quality part made in the USA. The 2004 has a dual cat system with piping down to the resonator so it is a little more expensive than other years. There are also four oxygen sensors on the 04 that fit into this assembly that you should replace (they are about $150 for the set if you get the exact fit ones that plug right in) I got the DENSO brand as they are quality and the best choice and won't throw codes. Altogether it was about $600 to get the parts delivered (and I had a 10% discount from CAR-STUFF).
As far as labor, it took several hours and lots of work to get at the bolts and do a little welding - I would estimate $400 minimum to have a shop do this for you. If you just have a regular cat on a TJ other than an '04 I think you get it replaced (part and labor) for $300 or so.
How much does it cost to replace the catalytic converter on a 1999 Toyota Tacoma
The Titan booster does not have a catalytic converter
That converter costs about $100
The average cost to replace a catalytic converter on a 1994 Cadillac DeVille is $700. This includes both the parts and labor.
The cost is $500 - $700.
Brown and Brown in Mesa Arizona is charging me $1300.00 to replace the catalytic converter and fuel filter.
$300.00
700
about $250
$1800
If a catalytic converter is indeed bad, it's far more cost-effective to replace it rather than try to repair it
$791 at the Lexus Dealer