Someone mentioned the engines being rock solid in the Cooper S ?? As far as I'm aware its the same engine in the 207THP GTI ??? which is far from solid !! Timing chain issues blight this engine you only have to go on 207OC to see the threads with upset owners.
Owned both the above cars the older Minis also suffer from electrical gremlins like seat belt, tyre pressure, airbag, lights appearing on the dash with no fault found just need resetting which is a pain.
An older Mini will cost a fortune to maintain everyone we take in needs £500 spend on recon and that market really seems to have slowed down now.
Good luck though if you get one hope its a good one.