Jeep Repair: Catalytic Converter & O2 sensors, jeep grand cherokee, grand cherokee

Question
I am wondering if replacement of thes parts in a 2001 Jeep Grand Cherokee has to be done in a shop? Meaning bascially, can I have any mechanic do it? I have been advised that JEEP has to special order the parts and since I need both convertors & all 4 sensors, it's gonna cost me approx. $2800 to get it done at Goodyear. I just had the transmission fixed ($3200) and I'm really not trying to spend that kind of money again in less than 3 months. How can you be sure that you need all of the sensors and both converters? I just want to ensure, I'm not being taken for a ride. Thanks in advance.

Answer
if u permit me to have the currant miles and last 8 of your vin I can see if the converters are covered under warranty   they have a 8 year 80 or 100k warranty.  U will get what u pay for if u go to a good year and use there parts. and what cost 3200 for the tranny????