Regarding Prot Evil items
Given the exteme cheapness of a permanent Protection from Chaos/Evil/Good/Law item (using DMG formula: ~4K) it would seem that nearly every character would want to equip one by the time they can afford it. The only reason for not doing so would be if the campaign featured a limited amount of such charm effects. But even in a campaign like this where charm stuff isn't terribly common, the items are still valuable.
When certain spells/items become "must haves" it's typically indicative of a balance problem. Protection from Evil as a spell does not seem overly powerful - the fact it can be dispelled and only has a limited duration balances it. The problem comes from allowing the spell effects to be turned into a permanent item. The 4K price is likely too low given all that it does. Given that many foes tend to be evil, this item potentially serves as all of these continually:
+2 deflection item (normally worth 8K)
+2 resistance item (normally worth 4K)
Total shield against most summoned creatures (hard to price, but seems pretty valuable)
Total shield against certain spells/effects (simple comparison is brooch of shielding vs. magic missile. A fully charged brooch is 1500 gold. A PfE item has no charges and stops more spells and effects so it should be priced higher)
Since all 4 effects come from the same spell, the combined pricing can use the "similar abilities" formula: 8K + (3/4) 4K + (1/2) X + (1/2) X. It's hard to pindown those last two prices, but lets say they are each 2K. The net price of a permanent PfE item would then be 13K which is a significant increase over the by-the-book simple formula estimate of 4K. This is one of those examples where the simple formula pricing breaks down.
