We bought ours from Kapiti Cars on Kapiti Road after a recommendation from a 'yocal' and we weren't disappointed, very happy with car (Toyota Prado), the dealer didn't blink when we suggested knocking a grand off the top, so makes me think we could've gone in lower : )
We were steered towards makes like Toyota, Honda, Mazda. We were told suburu parts were expensive (bizarre when I see them absolutely everywhere). I wouldn't totally rule out trademe though.
We did visit Wholesale Cars Direct, but found although they had a good range of cars they were definately from the 'used car dealer' school and just pushed us towards cars we couldnt' afford regardless of us telling them our limit.