Tibia as an ORPG with markets has an economy that is altered by many different direct and indirect factors.
The prices of the equipment, the consumables, Tibia Coins and valuables are fluctuating constantly due to them, may be events due to an update of the game, a world change or just the trend of the supply and demand of the players themselves.
All these can be analyzed to have a better perspective of the market and the economy of Tibia/