Few months ago, Bandai had on their website a picture of an boy underwear pack with a Ranger Key. But I had checked Target, Wal-Mart and K-Mart and found packs of underwear without keys. But now, someone spotted one.
Airflow Fox at Facebook bought a pack for his kid. It had the opaque Silver Ranger Key that was only available with the Silver Ranger Halloween costume. So if you were unable to get it, check out the underwear pack!!! He found it in Wal-Mart in Michigan.
Hopefully more keys pop up in these packs like Blue and Yellow, maybe even Green (hasn't been spotted yet)!
Razzle1337 found Blue and Red:
Related: http://henshingrid.blogspot.com/2014/08/new-silver-ranger-key-variation-in.html | http://henshingrid.blogspot.com/2014/10/toy-week-all-yellow-ranger-key-mystery.html