I actually was in my local Gamestop friday, asking if they could call around and check on Captain Falcons and Pits at the other stores in the area. The manager of the store was getting genuinely pissed off - not at me, but at a restock of both that had just come through the system a day before. Except at every single store he called out of about 10, scalpers had been calling the stores constantly, sitting on the phone for hours until UPS dropped their boxes off that morning. At each store usually one person had told them to hold 5-15 copies of each amiibo then ran over to buy them all.
My manager was angry because 1. Nintendo wouldn't set a limit, yet they get punished for breaking street date on a game by an hour, 2. Gamestop corporate woudn't set a limit, and 3. other store managers didn't just say fuck it, and set their own in-store limit.
It does seem like, if they wanted, Nintendo of America could set a sales limit with consequences for a retailer breaking it as with hard street dates. But nobody thought about it or cares if normal console owners/fans can buy Amiibo. I was told by the local GS manager that he doesn't like scalpers because they're usually not regular customers. A hot product will sell regardless of who the customer is, but honest customers stand a higher chance of returning to the store or buying other stuff while there.