David,
There are plenty of these cars out there and I would definately recommend purchasing in Florida since you are located there. As far as things to look out for, best thing to do is have a pre-purchase inspection done at a dealer or qualified mechanic. Here are a few things just to qualify the car for a PPI:

1. Service records, got to have them or access to them through the dealer.
2. Like you said, harmonic balancer is an issue so check for replacement.
3. Catalytic convertors - for some reason these seem to fail on a lot of W210's. THey are expensive but cov ered under warranty (8/80) as long as the car hasn't had an accident.
4. Rattling at idle - can indicate belt tensioner issues (a few hundred bucks)

I'm sure there are a hundred other things. I would recommend looking at a 2000 model for the updated interior.