Every other repair I've made to older cars has been relatively painless compared to the price of a catalytic converter. Radiators, head gaskets, clutches, and brake master cylinders were a couple hundred bucks. But catalytic converters? Some of them are up to $2500 just for the part.
Electric cars have their own long term reliability issues, but for gas cars my main problem is the cat. Everything else lasts with good maintenance. Unless it's a Chrysler...
One of them blew a transmission which was the end of that obviously. Another one had an ECU error but drove normally so I kept it until I left the country anyway.
But a cat never failed on my and then I'd just switch to another car anyway. But I've never spent more than 2200 on a car anyway :) The last one was not bad though, full leather heated seats, automatic everything etc. Really nice condition too, it's just that big cars are really unpopular and thus expensive here due to the road tax.
But these days I just don't even bother with a car anymore.