Actually, you do not need a receipt if you register it. It was a gift and grandma did not put the receipt in the package. Canon will cover it, since its a USA model, and it was registered.
It doesn't mean you are under Canon 1yr warranty, unless you can show the sale receipt from an authorizeed dealer - in this case BigValue is not.
Enjoy your new toy
I think they serve their own warranty?
Our products are covered by a warranty of 1 years parts and 90 days for labor. Due to our very low low prices, we are prevented from listing our items with manufacturer warranty. Rest assured, our products are the same as if you bought in stores