sometimes you get lucky and dont have to pay with usps.. I got a bunch of behringer gear on ebay awhile back and didn't have to pay squat.. otherwise like veeman says for electronics it's a $5 brokerage fee and then pst + gst.
UPS/fedex brokerage starts at $20 for anything $20 or less and goes up from there... I bought a used amp off a guy in the states 6weeks ago for $385 shipped and UPS wanted $98 for tax and their brokerage fee..
He was supposed to declare the value low and as a gift which he didn't...so I was like 'F-that' and had him fax in new paperwork saying it was a warranty return... so I got the amp, followed by a bill in the mail for $56 in brokerage...
To bad for UPS I don't intend on paying it...