They had this:
Other Considerations: Once you have a final cost figure, reduce that number if either of the following conditions applies:
—Item Requires Skill to Use: Some items require a specific skill to get them to function. This factor should reduce the cost about 10%.
—Item Requires Specific Class or Alignment to Use: Even more restrictive than requiring a skill, this limitation cuts the cost by 30%
Agreed that it was a little cheesy, especially if a DM isn't watching.
It's really a very tricky thing to allow PCs to craft magic items. If you give them enough down time and they take the right feats and classes then they can be way above WBL and make all sorts of odd things...
That is one of the things I don't like about Pathfinder changes, that there is no XP cost for anything anymore, crafting, spells, etc. It SHOULD be a cost and a big decision to craft an item and/or alter reality with a Wish spell. eh... c'est la vie.