Can't comment on Australian side, but in NZ part 135 operators are quite thinly stretched. 135 certificate is fairly expensive to maintain and having a good aircraft or two, in decent cosmetic state would make quite a dent in the owner's pocket. Tourism in NZ is not known to be heavy small-aeroplanes hit so my uneducated guess would be - possible but expensive, risky and prone to go belly up in a very short time.