they will take canadian cheques, and if their virtual support is half as good as their dedicated support, you'll love it there. go to their site and pop up their sales agent window. you can talk to them directly.
You can also go to a bank and get a US$ money order printed up. Then, you just make it for the amount on the invoice, and you're good to go! We have clients that pay this way, and they seem to be happy with it. It may be a little more work for you, but at least you will be able to select from any provider that accepts money orders.