186k on a ts
Why not? - serviced properly, there's no reason whatsoever not to get that. Ours is well past 120K and there's no sign of any issue with it......
As to Dave's query - ideally look for service history, but be realistic related to your budget - if you are looking at a 10 year old car, its unlikely that you'll have a dealer history - an owner's record where he's kept the receipts for all the parts he's fitted is probably more indicative of a well kept car than any random garage service receipts. You are particularly looking for cambelt changes - every 36K on the TS, maybe 50 - 60K on the diesels or the V6, and you want the tensioners changed at the same time, and for the 1.9 16v and the 2.4 20v, the water pump shuld have been changed at the same time.
156s of a certain age - anything over 5 or 6 years really, although the older cars don't seem so bad - can suffer from floorpan rust issues, so check that, particularly under the driver's seat, and around the rear floorpan edge, near the seatbelt mounts. Front suspensions very often have clonks and squeeks, from wishbone bushes and anti-rollbar droplinks, but it needn't be a show-stopper, as they aren't megabucks to change, though good quality items aren't cheap.
Other than that its just routine second-hand car checks - though particularly on a TS, check the oillevel and oil-change history - these engines do not tolerate low oil level well, and some (not all) TS engines can use quite a lot of oil - 1 litre per 1000 miles isn't unusual, so if owners have been in the habit of checking that's a good sign.
Just in case this sounds all doom and gloom - these cars can provide fantastic value for money purchases.....I'm a "bangernomics" exponent, and have bought many 156s at sub£1000 prices, and run them with minimal maintenance for 2 - 3 years, simply choosing to maintain essential safety related items, but not spend significant money on a car of little economic value....there are people on here who would have you hung drawn and quartered for not changing a cambelt at £200 - £300 a pop exactly on the 36K / 3 year mark - I take the view that on a £500 car its an extravagance, but its a judgement call. My feeling and experience is that with the revised tensioners, belts are less vulnerable, and that very few fail on age grounds unless you are talking 10 year plus, so a 20K mile car doesn't need a change after 3 years, whereas maybe one that has done 60K miles in that time does. BUT - that's my take, and I don't offer it as a guarantee - it just depends on your attitude to life. one of the reasons older Alfas are so cheap is the reliability paranoia - I use it to my advantage....