Joe,
Neal and I were playing around with more or less the same idea that you expressed and I think we've found a system that worked. Neal wanted me to present it to a community forum to get a general feel of audience approval so here's what I came up with.
We took HHH into consideration as being a continual spell effect item with a 1/2 adjuster as the spell is a long duration spell....
aka
5th level spell x 9th level caster x 2,000gp x .5 (long duration)=
45,000gp for Base Cost.
Okay, HHH is listed as having a price of 2,000gp.
We divided 45,000gp by 2,000gp and got a division modifier of 22.5
We played around with this and found that it when our prices were divided by this it produced prices pretty close to our estimate values for such items (based on their powers and comparisons)
22.5 is ALMOST 23.... 23, Dr. Pepper, wicked movie.... all sorts of bad stuff woooooo....
