Other Factors to Consider
When trying to identify your customer base and deciding how many items to post of each category, consider your server population and how it is split up between different classes and levels. You can find this information on wow.realmpop.com. Once you're there, you need to know what you're looking for, how to find it, and why. Also, it's worth noting that this site is only updated weekly. Its stats are based off of characters that post on the auction house, that character's guild, and everyone in that guild. This site is unable to record anyone who is guildless, and anyone in a guild with no one selling on the auction house. That being said, this site covers ALMOST everyone and can be used as a relatively accurate representation of the WoW population.
Since we are already using 77-79 cata greens as an example, this is the audience we will target for this example.
First, select a region. But before you do so, make sure you read the whole page so you have a full understanding of the data that you're looking at and where it comes from.
Once you've selected a region, you'll see this page. Here you can sort by the different categories as listed on the pie charts (mmmmm pie) or you can select a specific realm from the scroll box on the bottom of the page. I'm selecting a realm since I want to be realm specific, when deciding what my posting limits should be.
Getting into the Details
After selecting my faction, I also set the level slide at the bottom for my target customers for the 77-79 Cataclysm greens market. Here, I can see what gear will probably be my best sellers, based off of the class balance of 380 characters. I add up like classes that buy the same gear. You can add your own weights to each class or you can use my weights as a reference. For example: Cloth users are made up of Priests (32), Mages (40) and Warlocks (29) for a total of 101 characters or 26.57 percent of my customers.
I can go into further detail, noting that of the three classes, there are only two specs who use spirit, both being from the Priest class. Going into this detail will change my percentages as I will be sorting my cloth gear into two groups: healing and dps.
People are less likely to pick a healing spec for their main spec, but.... since we're talking about leveling players here, I'm going to weigh each spec a little differently than I would for level 90 characters. I'm guessing that 40% of the Priests are healers, and the other 60% are dps. Of course, I could be way off, one way or the other, but I'm going with my gut and game experience to come to these types of conclusions. Of the 32 priests, my guess is that there are 12.8 healers, I'll round that up to 13. Meaning I have 88 cloth dps characters to sell to.
I've finally come to a conclusion that about 23% of my customer base is cloth dps, and only about 3% are cloth healers. Doing this for each gear type will give you an idea of how many 77-79 greens you should be posting at a time. Not all of these characters will purchase gear, and not all of them will purchase it from you. Some players hold onto these greens for their alts when they see them cheap on the AH or pick them up while doing something else. After gathering all of this information I've concluded that I should sell 1 healing piece and 3 dps pieces per equipment slot, not counting rings, which are doubled since rings take up two slots.
After sorting out the cloth wearers, I do the same for the leather, mail, and plate wearing classes. Once I have all these numbers together, it's time to set up TSM auctioning groups for these items, which leads us to part 3. Part 3 will be live next Friday PST.