Ultimatley a car's only worth what someone will pay, so you may need to adjust price?
I've sold/bought my last couple of cars through TradeMe (although your local Turners auctions will sell it for you too?) - IMO have a low start price and a reasonable reserve, that way if it doesn't meet reserve at least you'll know how the market values it.
I would mention going to Oz - buying a 2nd hand car is always a minefield and at least prospective buyers know there's a genuine reason for sale (you can always say a friend will sell it on your behalf after you've left!).
Matt