Check on Canwax on ebay i've only heard good things about them and it's are made in Canada. You can get like 1.6 KG for $56 shipped to Canada or the US. They make 4 different kinds whcih ends and you can pick a total of 8 200g bars to make up your order so you can tailor it more to your conditions. They also have some cheaper options like 4 50g bars for like $9 + Shipping. Once I run out of the stuff i have right now i plan to pick up one of those 1.6kg deals.
Here's the ebay link:
BULK CANWAX Slide Ski/Snowboard Wax 1.6 kg ski wax - eBay (item 230545055769 end time Nov-30-10 06:46:55 PST)