The Magic Number is...
Blizzard stated in their latest conference call that the cost to upkeep WoW running since 2004 was set at 200 million USD.
While this may sound like a lot of money, remembering that they have to pay staff, servers, etc, and get way more than that in player subscription fees, it's not a bad number at all for Blizzard!
As stated by Kotaku,
You run a game for around five years, you can't expect it to be cheap. You've got to run servers, pay customer service reps, pay for marketing, etc etc. World of Warcraft's been running for four years now, so how much has the upkeep cost Blizzard?
$200 million. Or, at least that's what Blizzard disclosed during yesterday's analyst conference call.
That's it. Staff payroll, hardware support, customer service (which, interestingly, they say is their largest department), the lot. Well, mostly - we think they're just talking the upkeep costs, not the original development costs.
You may view Kotaku's whole story on this subject by clicking here!