Bearing in mind that one mans diamond is another mans turd and you should always try and play a game before you buy it.....
Terminator 2 - Cool game with a shallow ruleset and good flow. The theme is awesome though and seems to keep the price up a bit on these compared to similar games of the era. Check for pf wear as these got played a lot on location back in the day and also make sure the cannon works. Price wise I'd be looking to pay no more than £1K to £1200 for a nice one.
Getaway HS2 - I love this game

Very fast game with a shallow ruleset, but really fun to play. Plenty of these about so you don't generally have to wait too long to get hold of one. The main things to check are that the supercharger is working as it should and that the gear shift level isn't broken, also check for pf wear especially around the rpm inserts. I know of a mint one that sold before Christmas for £1K so don't look to pay more than this ideally.
Corvette - Great game with a deeper ruleset than T2 and HS2. You don't see this come up for sale that often so you might be waiting a bit to get hold of one. Check that the engine is working and not damaged and also the car race thing on the right side of the pf. I'm not so sure on price for one of these but for me I'd probably go up to £1500 - £1600 for a really nice one.
Dirty Harry - Awesome game with a great ruleset and strategy (In GrizZ's words, one of the best bang for buck pins out there). Things to check are that the gun is working, wear around the HQ hole, that the Magna Force magnet works and the ramps aren't cracked or broken. I sold mine for £1300 about 2 weeks ago and that had been fully shopped with the only bad points being 1 vert line out on the DMD and some scratches on the cab. Without those issues it I could have probably asked for another £100 so say £1400 as top price but bear in mind that game had been fully stripped down on the top for shopping and all the mechs underneath stripped and cleaned.
All the above is just my opinion of course and the right game to you may be worth more or less than what I think

Hope that helps.