So I went and pre ordered my Amiibo's today at Gamestop because yesterday I noticed that some are now unavailable.
Amazon.ca right now is out of stock on 5/12 Amiibo's (Samus/Marth/Fox/Villager/Wii Fit Trainer)
Amazon.com right now is out of stock on 3/12 Amiibo's (Marth/Villager/Wii Fit Trainer)
Gamestop still has them all available for pre order but I'd act now if you are seriously considering getting these just to be on the safe side