Beginning on Friday, September 11, Nintendo will release amiibos every month for the rest of this year. We have all, (or at least those of us who do not use amiibos for their intended purpose), waited a long time for wave 5b to release, (Zero Suit Samus, Olimar, Bowser Jr, Dr. Mario, Ganondorf, and Modern and Classic 8-Bit Mario). Most retailers have decided against being able to do in-store pre-orders and will just be releasing them on the day of, (including Amazon), but Reddit user amiiboMobTeam posted a pretty accurate guesstimate for the in-store inventory of these amiibos in different retailers, even those exclusive to certain locations, (Bowser Jr and Dr. Mario). The only thing that can be listed as a concern is the lack of information regarding an individual release for Modern 8-Bit Mario as he seems to only be bundled with the Super Mario Maker Wii U bundle.
Despite that, it looks like every retailer will be pretty well stocked on these figures in-store as well online, (at least at Target), according to another reddit post. If for whatever reason you cannot pick up your favorite characters on that day, other alternatives are available through Amazon using a price tracker provided by Nintendo Inquirer. However, if you want to press your luck at finding these amiibos at retail price, Toys R Us and Best Buy are limiting one of each amiibo per person while Target is allowing two per person. Other amiibos available this month are ROB, Duck Hunt, and Game & Watch that are only available as a 3-pack that is STILL available at Gamestop, (available September 25).