Obtaining a new title is very state dependent, here is Washington state there are a number of hoops to jump through. The big question is whether or not the seller ever had the title transferred into their name. If no (say it was bought as a parts car or something); then it becomes more difficult although not impossible by any stretch. Personally I would put this on the seller before any money changed hands, he has the burden of proof that it is his/her car and that they can legally sell it. Just because he/she bought it doesn't mean it wasn't stolen or otherwise contested. I have heard many horror stories of someone buying a car, then going through the process to get a title only to discover that somewhere down the line the car was stolen or sold by a family member who didn't have the authority to sell it. The problem here is that when the police research the VIN and should it come up as stolen, the car will be seized and returned. The new buyer is left with no recourse other than getting a lawyer.
Bottom line, you need the buyer to prove its their car and that they have the right to sell it. Since you are in NZ, you are a perfect candidate for a scam as the buyer hopes the car goes off shore and can't or wont come back to them. The rising value of these cars has made them perfect targets for people to make a quick profit and there are more than a few people who think that a car that looks abandoned is theirs to take and sell.
Point in case, a friend of mine was trying to purchase a vehicle that did not have a title, the seller swore it was their car and that the title had merely been misplaced. My friend contacted the DMV (prior to buying) as they will give you a name of the last registered owner (only a name and city, no address or contact info), he in turn did some internet searching and narrowed it down to 2 names, he called the first who stated they never owned such a vehicle however the second person immediately asked where the car was. Turned out that the car had sat beside an old gas station where the car had been taken for work but had closed down, the family meant to go and retrieve but were slow in doing so and when they did go the car was gone. They didn't file a stolen vehicle report as it was "just an old car" but they definitely wanted it. Long story short, my friend passed on the seller's information and the family got the police involved and retrieved the car, the family ended up selling the car (with a new title) for less money.
As the saying goes "buyer beware"... Not saying this isn't legit but I would definitely make the seller produce some documentation before I gave them a penny. You might lose out on a great car by pushing but that beats losing a pile of money on a bad deal. The seller can file for a lost title if it is in fact their car.