Quoted from Edster:Can't you just keep the money in your Pay Pal account as US balance and use it to buy US stuff in the future? Just don't cash it out. If it's not a huge amount of cash you're bound to buy something in the US ie parts in the near future no?
This is what I do and it does work, as lately as this week. My account balance shows me how much money I have in USD and how much in CAD. When I make a payment in USD, I select for the money to come from my PayPal balance, which is defaulted to USD.
Another trick after setting the PayPal default to USD is to attach a USD credit card to your PayPal account (BMO offers one to Canadian customers) and have PayPal bill USD to that card, or choose a CAD credit card that doesn't charge currency conversion fees (BRIM Financial and Rogers have one, I think).