Do you live in southern California? Because that's been the case with amiibo around here: You have to get them the day they come out if it's not Mario, Pikachu, Kirby, Link, Peach, Bowser, Sonic, or Pac-Man, because otherwise collectors and scalpers will get them all. That being said, some of these scalpers sell their stuff at collectible shows and are in heavy competition with each other. Frank & Son Collectible Show is one such case; while you won't be seeing them at the US$13 retailers would have them for, even hard-to-find ones like Jigglypuff and Ness are never more than US$25 (and the Inkling 3-pack has been there eveyr visit I've made since Splatoon came out) because these guys are in competition with each other.
The onus is still on Nintendo for vastly underestimating the demand for them and not meeting them when it's become apparent. Either they're having technical difficulties with a good manufacturer, or they're not taking the amiibo as seriously as they ought to be.
Nah, I live in Damn Stupid Hole in the Ground, also known as Illinois. As you might guess, I'm not very fond of it. I'm also sorta in the middle of nowhere (it's all farms and unending grass here), but even if I go north to the major shopping district that's nearby.... yeah. Marios everywhere, but nothing else. No collectible shows or anything like that around here. Stuff doesnt HAPPEN here.
As for the things being in demand and such, someone I know likes to go on about this issue, claiming that it's not Nintendo's fault, that it's all the retailer's doing (whichever one it is at the time), because they just wont order any of the more obscure amiibos to stock, because those dont sell. Hell, he claims that pretty much the entire thing isnt Nintendo's fault. He does this in extreme detail.
I have a hard time with that idea though, considering that A: the rare amiibos are bought out almost INSTANTLY whenever they do appear, and people tend to get just a BIT bothered when they cant find them, and B: the common ones that supposedly sell oh-so-well just sit on the racks; those racks pretty much never get restocked, because they never SELL. It's the case with absolutely every store I"m aware of in the area... and I'm aware of LOTS of them.
I only have 5 of the things myself: Mario, Bowser, Pac-Man, Donkey Kong, and Wii Fit Trainer, which I was very lucky to get because I just HAPPENED to be at the store on the one and only day when they stocked a few of them; pure coincidence, that.
Whole thing though frustrates me so much that I havent bought any further ones due to not wanting to support it.