In a word,The inflationary cycle has been an ever-present fact for each significant expansion pack version. They are caused by several factors, but in my opinion, in accordance with the monetarist view of inflation economy, is the most important factor in the dramatic increase in money supply. The money supply is increasing for several reasons.
1.Missions cataclysm reward more experience and greater value (suppliers) of the objects of reward in WotLK
2.The end of a given expansion is always marked by a period of great savings. Raiders often stop assaulting several weeks or months before an expansion and a general trend of safeguards. Resulting in huge cash reserves to be quickly dumped into the economy at the launch of Taste.
The second point is particularly interesting because the last year of upheaval has been perhaps the biggest increase in WOW GOLD rich kids in the history of the game. The world's first player to hit the wow gold cap was January 2008. Since that time, but mostly because WotLK freedom has produced a large number of players hitting the wow gold cap, or at least, accumulating vast amounts of wow gold.