I don't think it actually works as you describe. But if it did, such that necessary commodities tend to be anchored, while high-end stuff climbs, don't we then have an automatic, built-in way to extract more money from the well-to-do, proportional to how stratospheric their wealth is?
Why don't you read about how it actually works. If you're American, your tax dollars are paying for the wonderful data collection and analysis the fine people at the BLS perform:
