Oh yeah, I got hit hard with our dear friend Mr. Taxman. When I bought a Clie from the states, I had to pay almost $100 CAN in taxes and service charges on my $300US Clie. Generally speaking, using the government couriers (USPS --> Canada Post) don't charge you service fees, just the taxes.
And if I remember correctly, they don't charge you any fees for items under $20, so if its an individual who sending something to you, ask them to state the value at or under $20.( But if something happens to the package, any insurance on the package itself is covered for only $20. Double edged sword it is

)