Keeping on the hamburger theme, here's a sentence which will make sense to about two of you: the economy of Diablo III has fallen through the floor after a glut of Horadric Hamburgers (a burger which is also a dagger) for sale on the game's real-money auction house pushed the average price from around £90 to just £7.50.

The Horadric Hamburger is a "legendary" item in Diablo III. It's hard to get, and can only be found in a secret level, "Whimsyshire". And yes, it's a Hamburger which is also a dagger. The game provides only the cryptic description:

The Horadrim wandered far and wide to gather the finest ingredients for their feast. Only the lone traveler sent to the Moo Moo farm failed to return. Diablo had laid a trap for the Horadrim, the Hell Bovine, who struck the traveler down before he could gather the final ingredient: cheese.

The problem with the Horadric Hamburger is that although it's classified as an extremely rare item by the game, it's actually a bit rubbish. The game models stabbing someone with a hamburger relatively faithfully. That is to say, it doesn't hurt very much. As a result, no player who is practiced enough to find the damn thing is actually going to use it. It's a bit like a solid gold tennis-racket.

So the natural reaction of all the players was to take this immensely rare, precious, thing which they didn't actually want and use a new feature of the game which debuted last Friday: the real money auction house. There, they could sell their valuable trinket for cash money, and use it to buy real hamburgers which they can eat, rather than stab NPCs with.

Unfortunately, it seems everyone else had the same idea. As PC Games Network reported, three hours after the auction house opened, the burgers were listed at an average price of £87.91, with 12 chancers going for the maximum price of £200. By Tuesday, it appeared that they had realised their folly. Although it's impossible to tell how many sold, the average price had plummeted to just £7.50.

Virtual economies are increasingly interesting to economists, because of the sheer wealth of data they can produce. Valve, the makers of the Half Life and Portal series, recently hired Yanis Varoufakis, who rose to fame analysing the eurocrisis, as their "economist-in-residence". The President of Valve, Gabe Newell, laid out his pitch to Varoufakis:

I have been following your blog for a while… Here at my company we were discussing an issue of linking economies in two virtual environments (creating a shared currency), and wrestling with some of the thornier problems of balance of payments, when it occurred to me "this is Germany and Greece", a thought that wouldn’t have occurred to me without having followed your blog. Rather than continuing to run an emulator of you in my head, I thought I’d check to see if we couldn’t get the real you interested in what we are doing.

The Diablo economy is far simpler than the one that Valve appears to be setting up, but there's still no shortage of teachable lessons. The key one from this story is the fallacy of the idea that goods have some "intrinsic" value. Produce - even a legendary hamburger-dagger - is worth what people are prepared to pay for it. No more, no less. In this case, the labeling of the item gave faulty signals, which convinced sellers that there would be more demand than their actually was. As time went on and none sold, they were forced to cut prices to a more realistic level.

The auction house has now settled down a bit. If it goes the same direction as the auction house in Blizzard's previous game, World of Warcraft, expect to see some very interesting case studies indeed.