Mask of Lies Reverse Engineering

[bootzin]

How much would a mask of lies without the disguise self casting ability cost?
I mean, simply the undetectable alignment and +5 competence bonus..

What if it was a +15 competence bonus?

[GilesTheCleric]

Per DMG 285, the cost of a skill bonus is bonus squared * 100 gp. So, a +5 competence would cost 2500gp; +15 competence would be 22500gp. The difference between those is 20k, so you can add 20k to the price of the item to find the cost with the increased bonus.

Edit: the mask is in MIC 115. The cost of the individual parts for it don't add up as they ought to (because the MIC realized that some items are way overpriced). For example, the continuous Undetectable Alignment ought to cost SL * CL * 2k (2 * 3 *2k = 12k, then * 1.5 for having multiple different abilities), and the Disguise self portion would be 1 * 1 * 2k * 3/5 = 1200gp.

[Crake]

For example, the continuous Undetectable Alignment ought to cost SL * CL * 2k (2 * 3 *2k = 12k)

You forgot the half price for having a duration of 24 hours or longer. Also take into account that it is a 1st level arcane spell on the beguiler list which has a minimum CL of 1, so 1*1*1000 results in a mere 1000gp for continuous undetectable alignment. When you remove the 1.5* cost for multiple abilities (which MiC does later in their magic item creation updates) the 4500gp cost still covers 1000gp for the undetectable alignment, 2500gp for +5 in a skill and 1*1*1800/5*3=1080 for 3/day disguise self. So only an 80gp discount

yes, I know I was calculating based on CL1 and the item is CL5, and the disguise self is a swift action, so should be calculated as a quickened spell, but eehh