Pogo has re-released 101 previously-retired Mix-n-Match badges today. These badges cost 16 gems each and are available until March 4th.
These badges were originally released in July 2007 and July 2016. You'll find these badges starting on page 2.
http://www.pogo.com/challenge/find-badge.do?searchtype=mnm&sortName=expires&sortDirection=true
(https://i.imgur.com/G2pcS8S.jpg)
It also should be noted that according to the front page of Pogo there is a sale on some badges.
" Back from the Vault"
"Use coupon code MATCHFEB18 to save 25% on up to 20 Mix-n-Match Badges."