*nod*
More importantly, there isn't any guesswork behind it.
Let me see if I can remember item creation rules w/o referring to the books. I am at work, so if my memory is way off, please pardon me.
Control weather: 7th level spell @ 13th level for minimum caster level. We will say spell completion since it has a command word. And 1/day.
7*13*1800*(1/5) = 32760
Endure Elements: 1st level spell @ 1st level for minimum caster level. This is a Use-Activated since it is always in effect.
1*1*2000 = 2000
Storm of Vengenace: 9th level spell @ 17th level for minimum caster level. This is a spell completion effect.
9*17*1800 = 275400 with some sort of discount to accomodate the 1/month affect.
Of course, we have already costed 34760 of the 48000 base cost. That gives us 13240 gp to work with. So, the presumed discount for 1/month is 13240/275400 or a multiplier of .048.
And that is without considering that since this item does not take up a space limitation, it is supposed to be twice as expensive!
IMHO - This is one of the worst case examples of where item creation rules break down in the core rules.
Yet, your system accomodates it. As a player, I like to go for the unusual items. As a GM, I like to encourage my players to go for neat items. I am going to have to take a second look at Artificer's Handbook. Unfortunately, I can't persuse it at the LGS, since they are just not a great store. On the other hand, I do have an online source I can probably pick it up from. And since he provides more help/advice/service in the few emails I have had with him online, than my LGS has to me personally in the past 8 years, I am more than happy to take that route!