Price Sources are price-based sources for an item, and will return a positive numerical quantity in gold/silver/copper such as 10g 52s 12c. Price Sources will return a numerical quantity in gold/silver/copper, and can be split between external and internal sources. External sources are provided by and/or calculated by TradeSkillMaster, such as
DBRegionSaleAvg from AuctionDB, and internal sources are derived or calculated from other configurations and activity you have set or recorded in the addon, such as
avgbuy. There are multiple Price Sources which you can use in your Custom Strings, the following are some examples.
Check the Which Price Sources can I use and what do they mean?? page for a complete list, and details on each specific Price Source.