Not sure about the Honda, but I've worked with Mini's since they were re-introduced into production by BMW
For that price you're looking at an early supercharged version. Little if any engine issues, very reliable.
As always try to get the highest spec possible.
Areas to look out for:
Noisy gearbox -whine when driving. Seen a few
Heavy/noisy clutch - relatively long labour time to replace
o/s engine mount - leaks black fluid on chassis leg
Sump gasket - leaks
front wishbone bushes - wear and split, a lot!
rear exhaust silencer brackets - break and leaves exhaust moving around
front seats - make sure they move forward on runners when flipped forward
dashboard - rattles. Easy fix if its the early 2 piece dash
BC1 - water ingress into o/s/f kick panel ruins main control unit
Airbag light - normally a repair loom under the seat required
Few other bits and pieces but by and large they're a cracking little car. Just make sure you check it over properly to avoid any issues.
Easy to tune too, a smaller supercharger pulley is about 1.5hrs to replace and gets you 30bhp easily
Good luck