They are great cars! If you buy one, have it inspected *very* closely as they do have the nasty habit of tearing diff mounts and floor pans out. Less so in the Z3 coupe as they make less power than the M, but still a problem. Reinforcing the floor/mount costs big bucks and BMW still won't acknowledge the issue. Even with that, I think I'll still keep mine.
http://www.thelargeglass.com/bmw/subframe/cases.cfm
If you didn't know it, the Z3 coupe is actually more rare than the M coupe.
You do know the Z4 coupe will be out soon too.........
Mike