svt contour catalytic converters

My engine light went on in my 98 svt contour some time ago and had it checked out. One slow responding O2 sensor and codes P0420 and P0430. Catalytic converters appear to be shot. Changing the cats is going to cost alot, and I have no choice but to get it done. Just curious if anyne else with a svt contour has had it done and how much it cost them? I am not much of car mechanic so doing it myself is out of the question. Also my car is close to 140,000 miles and I am hoping this engine and car last until 240,000 miles or more, is this unrealistic? I drive fairly conservatively most of the time, do regular maintainence and so far the engine still sounds great and besides the cats have not had any other major issues.

fix it for as little as $70
http://www.trubendz.com/home.asp?producttype=exhaust&productfor=cougar_testpipe&productid=1001925&pagetype=detail

or buy an aftermarket cat for $130
http://www.trubendz.com/home.asp?producttype=exhaust&productfor=cougar_testpipe&productid=10019925&pagetype=detail

I'm guessing its the exhaust mainfold cats and not the main cat. In that case, its going to be a brutal raping of your wallet with parts and labor.
Even though you may not be looking to mod your car, I'd honestly look into a set of headers, or at least gutting the exhaust manifolds. Headers can be found for as cheap as a few hundred dollars. Gutting them is pretty much free if you do the work yourself. You will need to either make or buy a set of MIL eliminaters to keep the check engine light from coming on.
As far as longevity, 200k+ shouldn't be a problem as long as you are on top of maintainence and don't abuse the car.

Thanks for the info. I live in NY with strict emission standards, so I am going to have to burn a hole in my wallet. Since I plan on keeping my svt until it dies, and if it lasts 240,000 miles or more(knock wood) then it is just water under the bridge.

If you gut them, they should still pass the visual inspection and should pass the e test as well since the main cat is still there. IIRC, the pre-cats are there to help reduce emissions at start up. As long as the car is warm when testing, you should be ok.
If you do replace them, take a look at the contour.org classifieds. Alot of people sell their stock manifolds when the get headers and for alot less than new ones cost.