If you're going to drive, it might be worth checking with the hire company if you can leave your car at Wellington, and pick up another one in Picton cos otherwise it'll cost you around $250 to take your car across on the ferry. :icon_eek: icon_exclaim.gif (Compared with about $40 if you're just a passenger!) I know that some of the companies do this but you'd need to book in advance I'd imagine....
Otherwise, Air NZ are doing some really good deals for one way flights from Auckland or Welly to ChCh. I think it's about $85? (So by the time you've hired a car and paid for petrol & ferry crossing, flying works out much cheaper.) Check out the website....
www.airnz.co.nz
Cheers,
Jodie