Inconsequenti-AL said:
For me. Applying the test of 'is it so good that I'd take it before any other item'... The answer is a yes.
I do not believe you.
Consider the following list of 10 items:
A. Headband of Intellect +4
B. Amulet of Health +4
C. Cloak of Resistance +4
D. Winged Boots
E. Bracers of Armor +4
F. Lesser Rod of Quickening
G. Pearl of Power IV
H. Bag of Holding, 1500 lb.
I. Amulet of Armor +3
J. Rod of Spell Penetration +4
Are you seriously suggesting that if you were an 11th level Wizard and could have
one and only one of the items of the above list you would definitely pick item J before all others?
Heck, I bet if I allowed players to choose 3 or 4 from that list of 10, most would not pick item J. I would put it about #6 on my ordered list of preferences, but that is partially a style thing. Even a pure blaster Wizard is definitely going to grab the Headband and/or the Rod of Quickening over the Spell Penetration item.
If Spell Penetration +4 falls somewhere near the middle of a list of ~16k gp items, then the (n^2 * 1000) price formula works. Either that or you have to argue that all items in the DMG are priced too cheaply.