I bought my 2002 S60 used with 21K miles on it in 2004. It now has 110,000 miles on the odo, and I've passed it along to my stepdaughter as her college car. I get it serviced regularly and it has not been overly expensive to maintain through my local Firestone service center. It's been an overall dependable car with only a few age related failures, such as alternator, water pump, strut mounts, etc. Nothing too big at all.
The one gremlin this car has, and it seems to be rather common with this series, is that it eats tail light and headlight bulbs on a regular basis. However, these are easy to replace by the owner, and I now keep spares stashed with the spare tire in the trunk.