Hi and a warm welcome to the forum. There aren't a great deal of differences between Gransports as far as mechanicals are concerned. They are price focused mainly on the LE (limited edition) cars commanding a premium over the techno cloth cars. Early 54-05 plate cars are almost all techno cloth with the vast majority of the later cars being LE. An LE gets the following:
Full leather heated electric memory seats, Leather inserts on dashboard, Leather door cards, Leather headlining, Electro-chromatic rear-view mirror, Xenon headlights, coloured brake calipers, Rear parking sensors, Becker Auditorium 200 hi-fi with Satellite Navigation, 6CD Changer and 19'' trofeo alloy wheels and Saetta badges on rear pillars.
All standard cars have the same suspension, gearbox (f1) etc. Custom exhausts are popular with enthusiasts, Larini and Tubi's are highly regarded amongst others. A good service history from reputable specialists is a must, a clutch wear % worn, ideally as little as possible or a new one as its circa £2000 to replace. Finally, any car should have a pre purchase inspection report to show there are no significant issues.
The cars do have few faults to look out for, but are very reliable cars. I buy and sell Gransports on a regular basis, so know most things to look for. Prices aren't so much age but mileage focused and condition etc. If you need any help I'm always more than happy to discuss whether you are or aren't interested in one of the Gransports I have for sale. I also have 2 more cars I know possibly due in soon too. Feel free to give me a call if you wish to 'pick my brains', number's on my website. Hope that's of use to you.