I use Mr. Color exclusively now. There are shops in Toronto and Vancouver with the paints on the rack.
I can special order Mr. Color paints in Edmonton, but I have to order then in packs of six of the same colors. I can buy the thinners/ retarders locally.
The cheapest and fastest way to order is from this location:
I order in bulk and have a complete set of Mr. Color at home. Each bottle is $1.50 to $2.00, for 15-20 bottles shipping is usually $10.00 from sealmodels.
For AK, I order directly from AK. I've paid as little as $2.00 for a bulk order.
I don't order anything from the US. Shipping is horrendous. I could probably order from Martians on Mars and get cheaper shipping than anything out of the States. IMHO, US shipping is the most expensive in the world, it wasn't always that way.