Air ride
If "Check Air Suspension" has not shown up on you dash, I wouldn't worry. Yet. Check your compressor by getting two big guys or a couple bags of cement and load them in the trunk. If it levels off, your good. If it doesn't, you could spend as little as $100 per bag and install them yourself or convert to Coils Springs for about $125 for the pair. The choice is yours.
If you dont agree with the diagnosis use your due diligence and have someone else look at it. Its easy to think that the dealer is trying to make money off you, its harder to comprehend, its a twenty year old car that their not trained on. That was the first year of the second generation TC. Things have changed since 1990.