Market Watcher 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.
Warning to Users:
There is a memory limit that will result in the deletion of your saved scans not long after 30 megabytes. It is strongly recommended that you both backup your scan data and keep Market Watcher's memory usage below 30 megabytes if you care about your scan data.
The file with your data is located here:
\World of Warcraft\WTF\Account\<account name>\SavedVariables\MarketWatcher.lua
How to Use Market Watcher
Once you have installed Market Watcher, visit an auction house NPC and bring up the auction house window.
You will notice two new tabs: History, and Scan.
First, you need to specify which items you wish to "watch." Click the History tab, then click Add.
The Add Item window appears. Enter the name of an item you wish the addon to track, or the item id of an item. This addon needs specific information about the items it scans to function correctly, so it will need to get this information by checking the auction house for it, your inventory, your trade skills, or by silently asking the server to bring up tooltip information about an item id. The item id can be obtained by visiting a WoW database website. Simply search for the item in question and get the number in the URL, i.e. "http://www.wowhead.com/?item=34057"
Once you have added your item, the edit item window appears. From here you can instruct the addon to record the scans of the item, how long to keep the scans, and whether to only record full stacks. Also, you may configure the addon to not display the scan results of items that do not meet certain criteria, such as if the item is too expensive (or cheap), or whether there are none for sale or not. This speeds daily shopping and allows you to easily notice when there are undervalued auctions, or if a market is ripe for your own auctions, or to hide uninteresting markets.
Once you have input all the items you want to watch for, click the Scan tab, then click the Scan button. If you do not want to record this scan, then uncheck the "Record Scans" check box. There are a couple of reasons you may not wish to record a particular scan.
First, scans can use up a lot of memory. In fact there is currently no limit to the memory usage of this addon - it is possible to configure this addon to use as much memory as you tell it to, so you must pay some attention to this if you record scans for many items. The memory used by the addon is prominently displayed on the History tab. To give you a rough idea of how much memory scans might use, 500 or so individual item scans uses up about two megabytes of memory. If you configured the addon to record 50 items, then hitting the scan button with record scans checked will use roughly two megabytes of ram after 10 clicks of the scan button. It is also important to note, however, that some items will use far more memory than others. Frostweave cloth or Infinite Dust scans will use much, much more memory than say, Nobles Deck scans.
Secondly, the more uniform your scans are, the more accurate some of the addon estimates and calculations will be. Specifically the price change indicators in the scan summary and the technical analysis indicators.
Once the scan is complete, the scan summary is displayed. Here you can see at a glance how many units are for sale and the cheapest price per unit. If you input a threshold value when setting an item's options, the price text will either be green or red depending if the item's unit price is below or above that threshold value. If an item has scans saved, a percentile indicating the price change from the last week and the last month is displayed. This allows you to quickly determine if an item is selling above or below market value.
Mouseovering an item's summary will bring up a tooltip that will list every auction of that item at the time of the scan, ordered by buyout price per unit. Clicking on an item's summary will query the auction house for that item, and bring up the results on the right side of the window. From here you can conveniently make your purchases in a compact, price per unit ordered list. Shift + right clicking a result will buy that auction out instantly. Note that the auctions listed on the right side of the window are actual auction house results, and therefore have multiple pages, so you may need to click the arrows at the bottom to find the cheapest auction as indicated in the tooltip.
Reviewing Scan Data
Now that you have a scan saved, you can bring up the scan on the History tab. Click the History tab and then click on an item you have set to record. If you have three or more scans, a price history graph is displayed, otherwise a display similar to Blizzard's auction house results page is displayed. You can switch between the two views by clicking the button at the bottom.
The list view will display the scan number and how long ago it was taken. To save space, auctions that are identical are merged and given a number in the # column. The number obviously being how many duplicates of this auction there were. Note that sometimes it will appear as if it did not merge every seemingly duplicate auction. That is because items have a hidden value associated with them. Blizzard uses this value to track certain details about items. (such as where they came from)
If scans are less than 12 hours apart, Market Watcher can deduce if any "Very Long" auctions have either been sold or removed by the seller. Likewise, if scans are under two hours apart, the addon can determine if a "Long" auction was sold or removed, and so on. Using some judgment, you can then determine which auctions are being bought out. If the top few auctions listed are labeled "Sold or Removed" then it's safe to say they were bought out. Auctions with bids are also indicated. You can use this knowledge to more accurately gauge an item's worth.
The graph display can visually represent an item's change in price over time. "Low" "Average" and "High" are the lowest buyout price per unit, average buyout price per unit, and highest buyout price per unit of the auctions in the scan on that date. "Actual" is the actual price. "SMA" is the Simple Moving Average, which is the average of the last 10 price points. "EMA" is the Exponential Moving Average, which works similar to the Simple Moving Average, except more weight is put on the more recent prices. "Trend" shows the overall price trend (if the price is falling, rising, or flat) of all of the scans.