Pricing of an Arrow of Charming

[Bardess]

The cost of an Arrow of Charming is 2,886 gp. How is this calculated?
The arrow has the effect of a charm monster spell and is single-use. It’s also a +3 arrow. Since magic arrows are enchanted in batches of 50, a single +3 arrow should cost 360 gp, plus 7 as a masterpiece arrow.
Charm monster is a 4th-level spell and the item’s casting level is 8th. For a single use, use-activated item, this means 4x8x50=1,600 gp. It has different abilities, so let’s apply the x1.5 rule. 1,600+367=1,967 gp, x1.5 = 2,950.5. Close but not quite. Where am I doing wrong?

[Taja the Barbarian]

Where you are going 'wrong' is in mistaking the pricing guidelines for actual rules: Pricing tends to be more of an art than a science when an item doesn't exactly duplicate a spell (note the Arrow of Charming has a potentially much greater range than Charm Monster and has the additional ability to 'charm' on behalf of another person).

Items that don't exactly duplicate a specific spell (and some that do*) are priced based on the effect it delivers (as compared to other magic items) rather than the spell used to create it.

*An item that effectively produces a continuous Mage Armor effect will not be cheaper than Bracers Of Armor(+4), regardless of what the formulas say...

[Pizza Lord]

Masterwork Weapons wrote:

The masterwork quality adds 300 gp to the cost of a normal weapon (or 6 gp to the cost of a single unit of ammunition).

366 for +3 arrow (give or take some irrelevant amount for the arrow)

4th-level spell would be a 7th-level caster.
4x7x50 = 1,400 gp. [1,766 gp. total]
So I get a different total which is a difference of 1,120 gp. from the listed 2,886 gp.
With a 1.5 multiplier it would be 2,649 gp. Difference of 237 gp.

To me, it looks like the 1,120 would make the most sense. So there must be an effect that's worth that amount roughly. Whether the ability to transfer the charm effect by inscribing another creature's name or the fact that it deals nonlethal damage (it doesn't look like it would negate the +5 bonus from being attacked by you, even as nonlethal though).
Maybe some bonus for being 50% reusable and recoverable on a miss?

But yeah, sometimes the prices are just set to what matches the power level of other items (though the inherent +5 to a target's save just from the normal, intended use of the item is a bit annoying... unless the cost would have been higher and it was discounted down from some higher price.) Normally I wouldn't consider casting charm person/monster to be an attack (for purposes of itself, though technically it is, as it would break invisibility), shooting an arrow at someone probably is, but that's all GM discretion.

[Mysterious Stranger]

You realize that this item is nearly useless if used as a magic weapon. By using the arrow to attack the target it gives them a +5 on their save. Since items use the minimum save for the spell this means the save for this item is normally 16, when you factor in the bonus for attacking that drops to an 11. That means that a target with no bonus their saves make the save 50% of the time.