The chances of finding one with MINT bodywork are very slim now.. (Altho, it does depend on your definition of mint)
They all rust on the arches (well, 95% of them..) and finding one which has been repaired properly.. is probably as slim as finding one which is mint in the first place.
I gave up.. so I got a Williams (basically the same things to look for when you buy one) which had rusty arches.. a few bodged bits of bodywork.. for the right price - at least then, you can get it fixed properly and know it doesnt look stupid and wont rust again!
Other things important, such as Service History - or at least receipts to show things have been done.. things like cambelt change is expensive.. so look for them to be done (they should all be done now.. every 5 years or 60k/72k depending who ya speak to! Evo say every 30k I think?!).
Erm, It really depends how picky you are.. I gave up looking for a ready mint one.. but then, Im mega picky..
Definetly look at a few tho.. and goto see them.. Some adverts for them make out they are mint, not a mark on them.. but when you get there, its a different story.
Personally, Id try and buy a standardish one.. bodywork wise anyway. Things like Exhaust, Filter etc.. would be ok.. they are easily changed if you want.
Good Luck!