I probably wouldn't get these anyway as I'm not collecting Mario amiibos, but even if I was, I would never fill out surveys for a "chance" to win anything. I'd just save my money and wait for the eBay listings to appear.
Seriously if Nintendo tries something like that I would hope their survey system would get spammed until their servers broke down. And knowing NoA that wouldn't take very long.
But no doubt, however limited they may be in the US they'll be easier to get elsewhere.
