My local dealer is Bell and Covill and have serviced mine for past three years. I think they are well thought of.

Bought mine privately off Pistonheads and bought the second one I saw without an inspection.

To be honest I don't think there is a whole lot to go wrong with these relatively speaking and they tend to be enthusiast owned so I would not hesitate in buying private again.

Great cars, good luck with the search.

I'd agree with limpsfield for the most part, they really are generally well kept. However I think there are some that have been neglected more than others so it's worth a look at more than one (or more) to verify. I just bought my 2006 Exige S privately off of PistonHeads but I'm glad I looked at more than one and shopped around for a while, the first one I looked at I thought was really clean until I saw the one I bought which was/is literally in new condition and somehow the odometer was reading 29k!

Edit:

As far as inspecting goes, if you're experienced in buying used cars then it's really just the usual stuff to look for, IMHO: basically look at the bits where they don't clean/detail and get an idea of the car-personality of the owner

I didn't have mine inspected by a third party but I've bought and sold a lot more used cars than most folks!

Good luck with the search!