I own a 97 and 93 850, first I would make sure all the maintance is done
you are almost at 60k which requires a major service, dealer usally charges
500+ bucks, you can have the vin# run for the maintance record to see
what work was done at a dealer, (nation wide data base)

I bought my 97 at a so called good volvo dealer in albany ny, got the car
home , nothing was done not even a oil change, down a qaurt, the air filter was black, If you are buying from a deal make sure the 60k service is done,
if its a private sale knock of some money if its not done,

problem areas: 50k to 80k,

recall on the heated seats
abs module (problem if you have the tracs option)
a/c evap leaks,
control arm bushings (any rattling in the front end)
ball joints.
timing belt (MUST) be change at 70k.
elec. seat rear tilt cable
flame trap (remove it/or clean it every 3000 mile).
motor mount (upper and lower)

these car need maintance you should get at least 110k more out of it.
this site is for problems so dont freak out reading all the posts