I'm in the Okanagan Valley in BC. I'm just building a smaller light for a closet type 2x4 tent, possibly a 4x4.
128sqft of your space x 30-50w's per sq foot = 3800-5000watts. Sounds like about 12 rows of 8 cobs. If you have the money to buy from heatsinkusa then you can get the same passive heatsink everyone else in the forums uses which is about 5.8"x36" with 4 cobs on each.
I wouldn't want to be hooking up 100 cpu coolers!!! The only thing that sucks is you'll pay over $100cdn just for one of your 24 heatsinks. I didn't realize you were doing such a big grow. You might end up getting a discount from Jerry at Kingbrite for an order that big but I highly doubt it will cheaper than ordering Vero 29's from Digikey.ca. I think people are getting CXB3590's for about $45-$50usd per cob. After tax and shipping you'll be paying about $100cdn per cob. Vero's are $36 each from Digikey so the math is easy