ThirdWizard said:
The caster level makes no difference in the belt's price, a 20th CL or a 200000000 CL will not change the price one bit. It doesn't cast darkvision. The caster level doesn't affect how darkvision works.
It doesn't HAVE to cast Darkvision for the spell to be the appropriate one when it flat out gives the user Darkvision.
I cannot help it if they stupidly used a different spell (Tongues which even so should have been CL 12 * SL 2 * 1.5 ten minutes per level spell * 2000 GP * 2 = 144000 GP Market Value, but they dropped it to 14900 GP, even using the minimum CL of 4 for a Bard would result in 48000 GP Market Value) in order to get a boatload of different abilities that do not even apply to that one spell, just in order to craft the item for a super cheap cost.
Plus, a change in Caster Level DOES affect the cost of a continuous or use activated item, regardless of whether it changes how the spell itself works. Just like it does for all items that have a set pre-requisite spell and a Caster Level (and even for items that do not have a set pre-requisite spell and merely a minimum caster level such as a +1 Longsword).
If you bump up the Caster Level by two or more, minimally you will make the item slightly more potent by making it more resistant to attacks regardless of how rare that is and regardless of whether other abilities of the spell is bumped up. Hence, an increase in cost.
But look at a Lantern of Revealing, the example item for Spell Effect Use-activated or continuous items. Example items should follow the item creation rules even if no other items do. It uses Invisibility Purge because that is what it does (i.e. it explicity grants Invisibility Purge just like a Belt of Dwarvenkind explicity grants Darkvision, but it does not actually cast the spell just like all use-activated or continuous items).
It’s cost according to the equation (and it is the example item for that equation) should be:
CL 5 * SL 3 * 2 one minute per level spell * 2000 GP * 2 = 120000 GP Market Value.
It's Market Value in the book is 30,000 GP. One quarter of the cost.
It doesn't cast Invisibility purge per se (like a wand) even though that is exactly what it does (with the exception that the item can be handed to another character or placed on the ground (PROs) and can be put out by certain spells like Gust of Wind (CON)). For all intents and purposes though, it is an Invisibilty Purge spell.
And, that particular equation would match the items in the book a LOT closer if it was 500 GP instead of 2000 GP and it used minimum Caster Level for the spell instead of Caster Level.
Some of the equations are just plain broken for certain types of items (Rings, Rods, Staves, and Wondrous) when you look at many of those items.
ThirdWizard said:
The first rule for pricing magial items is to check against other magial items to figure out around what the item should be priced, anyway. Don't worry so much about what the tables say unless all else fails.
Ah yes. WotC's "we totally screwed up some of the equations and are unwilling to fix them, so either use a similar item, or hack down the price yourself" rules.
What a joke those subjective caveat rules are.
