Pogo has put some Mix-n-Match badges on sale for 10 gems a piece. There are twenty in total on sale — if you purchase them all you’ll be saving 120 gems in total.
The badges are in Backgammon, Battle Phlinx (x2), Checkers, Chess (x2), Cribbage, Dominoes, Euchre, Hangman Hijinks, Jigsaw Treasure Hunter, Payday FreeCell, Phlinx, Poppit!, SCRABBLE, Spades, Texas Hold’em Poker (x2), Trivial Pursuit Daily 20, and Tumble Bees.
None of these are expiring very very soon, but you’d probably be best picking them up while they’re on the cheap. To find the Mix-n-Match badges on sale that you don’t currently own yet, click on Find a Badge and then the On Sale tab.