Magic item creation rules question

[Railak]

So under things that reduce the price of magic items it has "item requires a specific skill to use" what exactly does it mean?

[KillianHawkeye]

Take for example the pipes of haunting (http://www.d20srd.org/srd/magicItems/wondrousItems.htm#pipesofHaunting) (and in fact, all the other pipes in the SRD's wondrous items page), which only works if you succeed at a Perform (wind instruments) check.

[Railak]

Oh okay, thank you, that clears it nicely xD

[Psyren]

I'll add that some items don't require you to pass a check, but instead require you to have X or more ranks in a certain skill - they would fall under this adjustment as well.

[Crichton]

Why wouldn't this item restriction/discount be put on every skill bonus item ever made, then, keyed to the skill that it's boosting? "I need an item to boost my UMD, so it's gonna cost (Bonus squared x 100gp)x0.9 and only be usable when the character is using UMD, or only if the character has 8 or more ranks in UMD" or "I'm gonna make a Cloak of Elvenkind, but this one only works when you have 5 or more ranks in Hide, so it only costs 2250 instead of 2500"

[Psyren]

Why wouldn't this item restriction/discount be put on every skill bonus item ever made, then, keyed to the skill that it's boosting? "I need an item to boost my UMD, so it's gonna cost (Bonus squared x 100gp)x0.9 and only be usable when the character is using UMD, or only if the character has 8 or more ranks in UMD" or "I'm gonna make a Cloak of Elvenkind, but this one only works when you have 5 or more ranks in Hide, so it only costs 2250 instead of 2500"

The rule of thumb that trumps all the pricing guidelines is to compare the finished product to an existing printed item and price accordingly. For all your examples, you'd end up with an item that is functionally identical to the existing item but costs less with no drawback, so the GM would be expected to make them cost the same. But if you do get your GM to agree to the no-strings discount, go nuts.

[KillianHawkeye]

Why wouldn't this item restriction/discount be put on every skill bonus item ever made, then, keyed to the skill that it's boosting? "I need an item to boost my UMD, so it's gonna cost (Bonus squared x 100gp)x0.9 and only be usable when the character is using UMD, or only if the character has 8 or more ranks in UMD" or "I'm gonna make a Cloak of Elvenkind, but this one only works when you have 5 or more ranks in Hide, so it only costs 2250 instead of 2500"

There are two things here.

One, putting a requirement to use a skill in order to operate an item that boosts the same skill doesn't make a lot of sense. You don't need to make a Hide check to wear a cloak, even if it's one that boost your skill at Hiding. Any item that has a requirement such as that would have to be use-activated, and most skill-boosting items are not.

Second, having a requirement of skill ranks to use an item that boosts that skill means that your item will naturally restrict itself to people who are already decent with a skill and just want a boost. This might be okay in individual cases, but you'd generally also want to allow for the case of someone who doesn't have any training in a skill and just wants to spend money to solve their lack in that area.

So you can add limitations to a Cloak of Elvenkind to make it so you need to be good at hiding to use it, and you also have to be an elf, and maybe even a worshiper of a member of the elven pantheon. Now your cloak is a lot cheaper to make, but very very few people can use it. It goes from being a general item that improves the Hide skill to an item that is only used by elven ninjas and hunters. Obviously, this isn't what the game designers wanted.