World of Warcraft: Wrath of the Lich King cheapest I can find atm. This expansion has been higher than cataclysm is recent weeks so might be a chance to grab it now incase it goes up again.
We've got a hukd guild and chat thread set up if anybody wants to join us:http://www.hotukdeals.com/misc/world-warcraft-thread-added-10-day-trial-links/857443
Also if you haven't used a 10day trial since using a paid subscription you should be able to use the wotlk 10 day trial found in the above thread before activating you cd key.
All are welcome to join the thread above :)