Help finding an old concept; natural RAW result being magocratic city-states

[johnbragg]

I am not sure that is it. Those use-activated items do come with a multiplier for duration or are single use per day. (And thus are more expensive than eternal wands or pearls of power as non casters can use them.) The once per round resetting traps must be from something more obscure and specific. There is a reason it is called traps. It is from some utterly unbalanced trapbuilding stuff that never considered beneficial apprications.

You may have a point, I may be using the wrong math.
Ring of invisibility, SL 2 * CL 3 * 2000 gp would give you 12,000, not the list price of 20,000.
EDIT: Footnote 3 doubles the cost of a continuous or use-activated item that uses a spell with a duration of 1 minute /level, such as invisibility. That gives an SRD price of 24,000, higher than the list price of 20,000. If the ring is command-word activated, that's *1800 instead of *2000, for a cost of 21,600

I don't have a RAW explanation for why ring of invisibility doesn't follow the rules. I can conjecture that it's because the duration of invisibility is usually shorter in practice than the listed 1 min/level, but that's me speculating, not RAW.

And for the teleportation circles, it's probably more economical to just permanency the darn thing for 4500 xp.

From the SRD, Lantern of Revealing is the example listed for "use-activated or continuous", the sort of always-on effect that a Tippyverse teleportation circle would be producing. CL 3 invisibility purge * SL 5 * 2000 = 30,000 gp which is the listed price. If you want to argue that a non-movable magic item should be priced differently than a movable one, I'd listen, but I don't think you have a RAW citation for that.

The numbers all match exactly with what you'd want from a Create Food and Water trap. 3rd level cleric spell.

If you want to argue it's unbalanced, that's fine. Nobody really said it was balanced. Just said it was RAW. And the game was balanced (to the extent that it was) for what PCs could do, not what millenia-old monarchs with arbitrary wealth could do.

EDIT:

If a continuous item has an effect based on a spell with a duration measured in rounds, multiply the cost by 4. If the duration of the spell is 1 minute/level, multiply the cost by 2, and if the duration is 10 minutes/level, multiply the cost by 1.5. If the spell has a 24-hour duration or greater, divide the cost in half.

So you would multiply the costs of the Teleportation Circles and the Create Food and Water stations by 4, since they have instantaneous durations. But it's still just money, which the Witch-Queen of the Shining City is assumed to have arbitrary quantities of. And once it's built, it's built forever by RAW with no maintenance costs and no time limits.