It all depends on your spending habits ;D and ofc, what spawns at the merchants. I got sick of waiting for specific items to drop as loot and went the easy route. I hit up every single merchant I could find, and bought the items to disenchant.
-A world to the wise, don't waste money on an item that you have already disenchanted because it has a stronger enchantment placed on it. Once the enchantment is learned, it's up to you and how much you level the actual enchanting tree to gain stronger enchants.