I sell items that have a cost/purchase/sell price attached to an Index. For example Aluminum, Zinc, Copper...
The Index at the London Metal Exchange (LME) for these materials changes intraday but for simplicity, I only need update my prices once a month.
If I could store the value of LME for Aluminum, Copper or Zinc in a single field and define that this or that Item is linked to that field, then I can drastically simplify the updating of prices.
For example: Item1 this month would be 'ALUMINUM LME' ($2) + Item purchase price ($3) = $5. Next month LME for Aluminum would be $2.1 so my Item's new price would be $5.1 As I have 100's of Items made of Aluminum, changing the LME portion of the price would update the whole thing. Similarly to Copper and/or Zinc.

At the moment I have a workaround, I have combined the prices in an Excel file and every month I would delete the price lists and re-import with new prices.