Realm's volume in sale for a given item
I would like to be able to use the total volume of a given item currently in sale at the Auction House of my realm for custom prices.
I will be able in TSM4 to get this info for the whole region using DBRegionSaleRate and DBRegionSoldPerDay, but for some items the volumes are very different in my realm, and I cannot always rely on region data (for example, Essence of Air has a Region volume of about 15, but a Realm volume of about 1 for the last month; I'm on EU-La Croisade Écarlate).
The data is available on the website, therefore I imagine it would be possible to have it in-game.
You probably don't want to use volume with very little data. Your best bet might be to start off the accurate region data, divide by the average players per realm, and multiply by the player count on your realm; you can easily find a realistic number by counting unique names on the AH api dumps.