Having brought back a 161 K mile 97 C280 that was sitting a few years:

The AC compressors are weak, mine didn't blow up it just didn't move enough pressure, an updated replacement Nippondenso is ~ $ 275. Both compressors have variable displacement and the control valve might have been bad on mine. For the cost of the uprated compressor, I wasn't going to piece meal things together.

If this car was driven in salt at all, expect the AC condenser to be corroded / leaking especially behind the aux rad fans ( if it has them )

Headliners fall down, they are supposedly removable through the passenger door while the door is left on. I'd suspect is is less of a struggle if the front seats are removed.

Have a close look for rust, with such low miles, driving a car once a winter on a wet salty road then never washing under car / driving in a heavy non salt rain is just as bad as driving through the entire winter.

It may need lower ball joints due to boot cracking / water intrusion.

With 21K miles I'd expect the car to have worn original tires matching the full sized spare ( Continental I think ) or very new tires on it currently.

The wood veneer around the radio / HVAC controls peels off and needs reglued.

97 is the last year for an actual key not the sometimes loses it's mind and quits working EIS electronic key fob.

The cabin air filter probably needs changed, under right side dash, easy to change.

I'd change all of the coolant hoses and the driver side plastic heater hose bulkhead to prevent future breakdowns, they are priced right when bought at the dealer and not worth chasing aftermarket.

These cars are built to a price ( 30 K ) and are not a R 129 SL ( 80K + ) , however they are good driving cars. ( Think German Toyota Corolla ) Car fax is OK for mileage history, but don't hold it all holy as some CF junkies do. Buy the car for what it _is_ not what some internet site says it is.

My SL was tagged in CF for having "moderate rear damage". At some point it got a rear bumper cover and after my purchase I pushed out a maybe 1/2" deep dent in the spare tire well. The steel bumper and tail light panel were original and untouched. I'd hardly consider the damage moderate but a CF junky would scream the car was "totaled".