Order Mega Man Zero Collection for $29.99 from the Capcom Store, and you will receive...
...two randomly-chosen Mega Man Zero buttons from the above assortment.
In addition, Capcom Unity's DJay advises "before you hit the Checkout button be sure and check out the Spring Blowout Sale going on now. You’ll find deep discounts on lots of great Capcom games and merch. The Capcom Store Spring Blowout Sale only lasts until next Sunday. Get your Capcom fix now!"
As for Mega Man Zero Collection, you can purchase that from Capcom here.
News Credit: GoNintendo, Capcom Unity