Cheapest I can find around. not sure how long this price will last.
The cheapest I got from ebay was £14 but that took a month to get that price. now it's £15, just pay and wait :) no need to use your luck.
and don't forget to topcashback it as well
Two New Playable Races: Adventure as one of two new races - the cursed worgen with the Alliance or the resourceful goblins with the Horde
Level Cap Increased to 85: Earn new abilities, tap into new talents, and progress through the path system, a new way for players to improve characters
Classic Zones Remade: Familiar zones across the original continents of Kalimdor and the Eastern Kingdoms have been altered forever and updated with new content, from the devastated Badlands to the broken Barrens, which has been sundered in two
New High-Level Zones: Explore newly opened parts of the world, including Uldum, Grim Batol, and the great Sunken City of Vashj'ir beneath the sea
More Raid Content than Ever Before: Enjoy more high-level raid content than previous expansions, with optional more challenging versions of all encounters
New Race and Class Combinations: Explore Azeroth as a gnome priest, blood elf warrior, or one of the other never-before-available race and class combinations
Guild Advancement: Progress as a guild to earn guild levels and guild achievements
New PvP Zone & Rated Battlegrounds: Take on PvP objectives and daily quests on Tol Barad Island, a new Wintergrasp-like zone, and wage war in all-new rated Battlegrounds
Archaeology: Master a new secondary profession to unearth valuable artifacts and earn unique rewards
Flying Mounts in Azeroth: Explore Kalimdor and the Eastern Kingdoms like never before