Hey, Chris here. I've been doing a bit of writing about the economy in Runescape, a surprisingly complex market to the point that someone can enjoy the game without ever leaving the Grand Exchange area where business goes down. There's been a lot of inflation of the gp (gold piece), the basic currency of Runescape, so large amounts of money are stored in discontinued items, very rare objects that never increase in supply, and thus only increase in value. Some notable examples of discontinued rares are 'pumpkin', 'half-full jug of wine', and 'halloween mask'.
The holy grail of rares, however, is the party hat, or phat. A blue phat is valued at a staggering 2.1 billion gp and is a symbol of immense wealth, and, of course, a huge number of hours poured into the game. To put this in a bit of perspective, in-game food in general is worth a few hundred gp per item. A decent set of armor would cost about 50,000 gp. Using the price of 'bonds', an in-game item bought from Jagex for 5 dollars and sold for around 6 million gp, a blue party hat is currently worth about 1800 dollars. Different sites around the internet advertise party hats at prices anywhere from 800 dollars to 2700 dollars. I'm very interested in the Runescape economy, but it's still staggering to me how much people will pay for virtual items.