Monado lend us your power, and also maybe your wallet.
Certain amiibo figures will be exclusive to different retailers, starting with Wave 3.
Wave 3 figures, slated for a February 2015 release, will be the first to be available as specific retailer exclusives. This info comes from a video on Nintendo of America's YouTube channel, which says that a "certain number" of these figures will be exclusives with Nintendo's retail partners. So far the only one we know of being an exclusive is Shulk which is listed as a GameStop exclusive on the GameStop website.