I've got the MK 2 "shrouded" version and have'nt had a bit of bother with it since buying it in October last year had loads of good hunting trips out and many a full game bag, however I do know the MK 1 version was prone to leaking valve seals, iffy triggers and pellet jamming. I am sure this does not apply to every MK 1 but it was classed as a common fault on many models, this is the MK 2 version I am currently using:-
As for the price I suppose it depends on condition, type of scopes/mounts, size of bottle & pressure it holds etc,
Regards
Coney.