Yes, this will be a US dollar transaction.
Don't panic.
Is your Paypal account tied to a credit card?
There is no fee to buyers for using Paypal.
Your credit card will do the foreign exchange (around that 88 cents CDN difference between the currencies) and a small fee, usually in the 2.5% range on the difference. (About 3 cents).
So we are talking pennies here.
That 2.5% is pretty average on credit cards, not particularly extravagant.