We have bought a few in from these guys -
http://www.tau-sales.com
This was about five years ago and I do not know what the story is now in regard to importing cars, but we had not trouble getting damaged cars in to fix and use for ourselves.
Customs wise, if you have a customs number you must get a customs agent to handle the import, MAF clearance and tax paperwork for you. If it the first thing you have imported into the country sometimes Customs will do it for you, but this may not be the case now.
Depending on the value of the car, sometimes the freight, customs, MAF and GST will cost you more than what you have paid for the car.