If you declared the value at $2500.00 USD I would say that most of that $700 is made up of tax. At the current rate of exchange $2500.00 USD is about $3967.50 CDN, tax here in Ontario is 15%, this makes the tax portion alone $595.00 CDN. Along with some brokerage fees and the usual processing fees I can see the total hitting $700.00 no problem. In this case duties are most likely not a factor unless the NAFTA forms were not properly filled out. When things are shipped from the US to Canada by courier you are almost certainly going to end up paying your provincial and federal sales tax.
Gene
Gene