"For a limited time, starting Friday November 23, you can find the World of Warcraft: Battle Chest for $5, Cataclysm for $10, and Mists of Pandaria for $20"
-- Retail Black Friday Offers (list of other retailers in full post)
I haven't been able to find the $5 Battle Chest on Amazon, but I figured this would help alert / save searching for some people, enjoy:
$5 Battle Chest, GameStop online
$10 Cataclysm, GameStop online
$20 Mists of Pandaria, GameStop online
*Awaiting Amazon $5 deal info*
$10 Cataclysm, Amazon
$20 Mists of Pandaria, Amazon
Snag up the deals while you can, and please post $5 Amazon if you find any!