Have a look at the buyers guide sticky, it will tell you what to look for.
The cam belt job is essential at 36K or three years, whichever is the sooner. Keeping the oil up to max is also essential, some TS drink oil, some don't but you still have to check it at least weekly. If the cam/auxiliary belts need to be done you should change the variator at the same time, an extra £100 or so but if you don't and the variator does get unbearably noisy you'll have to do the whole job again. Some people also recommend Water Pump replacement at this time as well, probably worth doing.
The suspension on these cars are probably the Achilles heels of these cars, when it's working well it's great but does have a hard ride, if you suffer from haemorrhoids look elsewhere !
However the rear components are expensive to repair when they have to be done, a lot of people go for Powerflex bushes at this point but I think I prefer to stick to OEM. Either way you'll need upwards of £500, could be quite a bit more. Don't ignore any problems in this area though, it could cost you a new subframe and you don't want to go there.
The TS drives very well and most people reckon the handling is perhaps a bit better than the V6 as there isn't as much weight over the front. Having said that my next one will be a V6 3.0L, I really do want one of these. My indy reckons that the V6 is perhaps more reliable than the TS but the bills will be higher if it does go wrong. The TS will return about about 28 - 32 mpg, the V6 about 10mpg less.
Look out for electrical niggles on all of them, don't discount what seems to be a minor problem, could cost loads to fix.
Now is a good time to buy if you have the cash, one guy bought what seems like a beautiful Cup for not a lot of money just last week. Take your time, have a good look around and don't be afraid to walk away if you have any doubts. Once you have decided to buy a GTV, which will have come from the heart as they are in no way practical, now buy with the head, as hard as it may be !
Hope you find what you want.