Hey man, if you want one straight away down in CHCH your best bet would be Rebel sport I think. Though be prepared for stupid prices, if there isn't a discount sale day it's horrendous.
If you are after Warriors gear in general- say Cap, backpack, poloshirts and training jerseys...I highly recommend you pop into New Brighton and have a look at a store called McCrakken sports center. They have really good ranges of reasonable priced gear for most NRL clubs. Great place to get something for kids when you're on a budget.
Trade me is always worth a look too.
The place I got my official Warriors and Kiwis tops from was an Aussie online store that advertises in the RLW...Jerseys.com.au. DOn't be shocked at the freight costs though-it isn't as bad as it looks. It comes up as an International standard post so looks eye watering. But they manually change it for NZ customers so you don't actually pay that. ;-)
Hope that helps.
