numsold as price source
My suggestion is to have the amount the user has sold (already displayed in tooltip and tracked via accounting) as a price source so we can use the amount we have sold as a modifier in custom price functions. An example could be for a minimum price. ifgt(numSold, amount, max(% minsell, fallback minimum price), fallback minimum price). In the retail version defining something as high volume could be done with a region rate, but due to the lack of API for classic these sources cannot be used there.