You can purchase three badges for the price of two using the coupon code BUY2GET1 at checkout. This code can be used more than once. “Note that the 3 for 2 offer says one per transaction, but the code is repeatable; meaning you can put 3 mix and match in the cart, apply the code and checkout [paying 32 gems], then put another 3 in the cart, apply the code and checkout again. You can repeat this as many times as you like; it will still only be 32 gems per 3, no matter how many batches of 3 you buy.” The offer expires 11/30.
But looking back seems Pogo releases Monthly Badges a day before the month starts, just like they do Jigsaw Detective. Maybe we will be able to get all of December Mix and Match 3 for 2?