Market Watcher is an addon that scans the auction house and records data for specified items and assists in daily auction house shopping in general. When the addon is set to record, a price history can be displayed to assist in determining a value for items of interest.

What makes Market Watcher unique from other auction house addons is that it records multiple scans instead of just the most recent. This obviously uses a great deal of memory, so only scans of items specified by the user will be recorded. The saving of multiple scans allows for a more accurate determination of value, and allows the addon to deduce if some auctions were actually sold, so you can see which auctions are actually selling as opposed to basing a value off the prices of auctions that may not be selling at all.

The number Market Watcher cares about the most is price per unit – particularly buyout price per unit. Lists are sorted by and comparisons are made by this price. For example, you might have the addon set to scan for abyss crystals, but not display the result in the scan summary unless the price is below a set value. If there are crystals for sale below that value, then the lists generated by the addon will order the auctions by price per unit regardless of stack size. The price history graphs use the lowest, average, and highest price per unit.