The inflation adjustments would need to be done on scoring the averages against the averages of other segments of the market; and then balancing that with the average increases in the transactions. My original post is a bit elementary to explain the concept in mind, but there could be measures taken to help prevent that issues. Items on the CPI could be rotating, to prevent sharking certain items for example.

Asiaine is right, I'm not saying that they aren't doing a decent job regulating things now (even if it is pretty hands off regulation)- and not even saying that this would be a measure to handle that entirely. I'm saying it could help make the NPC goods an active part of the changing economy. And in regards to things like INT materia, and etc, every market will have it's tulips.