I brought some stuff from OCZone a while back and they were very helpful, what they didn't have in stock they offered an upgrade at no extra cost
In saying that tho, I wanted to buy a microSD card from them and the postage was going to be about $9, I asked them (email) if they could just throw it in an envelope and charge me 50c they just didn't reply to me

PBTech in Hamilton are good, as long as you deal with the right people there, they give reasonable discounts and are often cheaper than advertised on pricespy or their website.  I've RMA'd a couple things through them too and its easy (could just be that I'm dealing with them face to face as opposed to over email).  They seem have pretty good relationships with most suppliers, and they don't really sell stuff from suppliers they don't get on well with (although they can get it for you if you ask).

Hamilton also has JayCare who seem to have some obscure components that no other stores carry in stock (like IDE/SATA converters)

And there's Tisco in Hamilton too, they never have anything in stock.  I went to buy a AM2 motherboard from them (about 6 months ago) and the only one they had in stock wasn't even listed on their website