[fleitz]

If most of your costs are USD and most of your clients want to pay USD why not open a USD account with your bank and be done with it?

Figure out the most fluctuation you could handle and put a note in your TOS that you will adjust the pricing based on USD/CAD exchange rates if they go outside of a certain window. Alternatively, you could bypass this calculation and just purchase a CAD futures contract from your bank.

Seriously, worry more about getting customers than how the USD/CAD exchange rate will vary over the next year or two and you'll do fine. It's more likely that the CAD will go to .80 than 1.20 because Canada exports 80% of it's goods to the US and a devalued currency is better for exporting countries.