From the announcement:
Zombie Horde Set I is on Special at Victory Force Miniatures for one week to celebrate Zombie Awareness Month.
To start Zombie Awareness Month off big, Victory Force has placed the Zombie Fan Favorite, Zombie Horde Set I on Special. There will be other zombie specials all this month. Look each week. The Month will end with the release and special of the Zombie Hordes Set II: First Responders.
See the blog each week for more specials