The World of Warcraft Battle Chest now includes Classic, Burning Crusade, and Wrath of the Lich King, all for $20. Existing Classic and Burning Crusade accounts seem to have been upgraded to Wrath of the Lich King for free! You can purchase all of World of Warcraft up to Mists of Pandaria for $60 now as well.


So MiRai was correct.

MoP is also 60$ from nothing and likely not to change.