Pre-ordering amiibos nowadays is nearly impossible, they are sold out within minutes. You have to be the sort of really dedicated person who hangs out in amiibo collecting communities to stand a chance at finding a pre-order window.
Yeah, it's kinda sad. I really like the amiibo-idea and would have certainly bought a few, but after my experience with the Shulk amiibo I'm kinda turned off for the most part.