Buying from International Vendors?

I'm doing some Economics (supply and demand) research on international online shopping. This is mainly targeted for U.S. buyers. Just wanted to get a rough idea before going in-depth with my project.

Do you buy products from other countries? For example, do you buy computer products from Canada? If yes, what are your reasons? If no, what are your reasons?

Also, is price the main determinant? For example, if a product is cheaper in Canada, would you buy it from Canada or would you rather pay a higher price and buy from the U.S.?

I've bought from Canada a few times, when products I was looking for weren't available in the US.