Here's one on eBay for $180.
http://cgi.ebay.com/Apple-MacPro-Ap...eZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem
Though honestly, if I were ever to NOT get AppleCare, it would be with a Mac Pro. That's the one machine that's easy to work on yourself, and if it's gonna break, it will more likely happen in the first year or well after three years.
Applecare is region specific one of the regions is North America, so you could buy american applecare and use it in Canada and vice versa. Also, if you live far from an apple store or authorized repair centre applecare would be a good idea because you will need to call applecare directly to have them send you a box to ship your computer back to their repair centre and without applecare you only get one phone call within the first 90 days of purchase of your computer.
L.A. Computer has some of the best deals on AppleCare of anywhere outside of auctions by the way:
http://www.lacomputercompany.com/cgi-bin/rpcart/featured.cgi?group=appcare
These are the retail boxes shrink-wrapped. I trust them much more than anything I could get on eBay.