The ANZFC Cessna 172RG Cutlass is $150/hr if your NOT employed by Air New Zealand, if your an employee you get a discounted rate ($135/hr on the Cutlass for example). The Cheapest aircraft would be the Cessna 150 which is $120/hr (non employee rate) from memory.
The basic process to join is to send away the membership Application form (found inside the 'downloads' tab). It can take a month or two to hear back from them (as there is no fancy 0800 number or receptionist). You pay around $150 per year as a member. Once you are a member just give an instructor a call (under the contacts tab) & arrange a flight from there. You book the flights on the website itself under the 'bookings tab'.
If you want to know more information your best bet is to give an instructor a call or I'll be happy to help via pm. The instructors don't work there full time or anything (not enough business there to make a living off) so they have other jobs. The whole place is casual, relaxed, quiet etc but as I said the aircraft are well maintained & all the instructors are great & several are highly experienced, these two factors are the most important thing.