The laws in Canada in regards to airsoft are diffrent, its a very long winded explanation, all you need to know right now is that if you order from the USA. Customs will more than likely seize your gun and you will not get your money back. The costs are reflective of the cost of a special licence that is required to have to import airsoft, not to mention tarrifs, taxes, importation fees, freight, shipping and packaging etc.
This website offers a Frequently asked question section, but before you read anything in there. I suggest you read this.
http://www.airsoftcanada.com/showthread.php?t=51609
It will reveal alot more information and make things a little more clear.