Are they talking about maintenance costs, or repair costs? Big difference, especially if the repair involves body work.
The biggest repair I had on my GTS was when a couple of pushrods gave up. It made a pretty horrible clacking sound, and I thought that was going to be an expensive one. But, thanks to JonB it ended up costing me only about $20 for a couple of pushrods (still have the other 18 as spares) and about a half hour of my own labor. Otherwise, it's been almost completely bulletproof. Can't say that for many other 13 year old cars I've owned...
As far as maintenance goes, other than being a pain to get a jack under the car, it's a piece of cake.
As long as you don't crash these cars, they're pretty darned easy to own.