Honestly, there is nothing you can do at this point. Maybe the seller made an honestly mistake with the price (eBay is now making some changes, so it is a bit confusing for sellers, they might have meant to list for 10 USD, but accidentally sold it for 10 CAD.) or maybe the seller is just trying to get some extra money out of you. If you don't want to pay the new "right" price for the camera, the seller will just give you a refund. It is annoying for you, but the seller will be penalized by ebay, if that makes you feel any better. Buyers back out of sales all the time, and sellers can too.