According to Eurogamer, the beta keys have sold as high as €652 ($1022) on internet auction site eBay's UK arm. Meanwhile, recently completed listings in North America range anywhere from $200 to $650, with one listing going for $735.
Originally distributed at Blizzard's BlizzCon 2007 and 2008 Worldwide Invitational, the keys were recently revealed to grant entry to the anticipated expansion's beta testing phase. The only other means of gaining access is by way of an opt-in sign-up page, from which participants are randomly selected.
Wrath of the Lich King marks the second expansion to the wildly popular fantasy MMO, and includes the title's first hero class, the Death Knight.
The expansion is set to make its full retail debut by the year's end.