So I am thinking of running a low magic game, and Magic items will not be able to be purchased and creating them costs as much as if you were buying. One of the only ways to get magic items is to make them yourselves. However, one thing I am thinking about adding to the game is special material components that can be used to bring the item creation costs back down to normal. Here is the idea:
Spoils of war: When ever you slay a Dragon, Intelligent Undead, or Magical beast, you can make an appropriate knowledge check, DC 10 + hit dice of the creature slayed to know about how to retrieve a "trophy" from the creatures body that has residual magical energy from the beast within. Actual removal of the trophy requires a survival check equal to the above DC. If the same person who made the Knowledge check is the one rolling the survival check, he gains a +2 circumstance bonus to retrieving the item.
The item retrieved can be anything off of the slayed creature, but only the first Item so harvested can be considered a spoil of war. Multiple, similar items can be harvested, along as they function as 1 unit, such as a collection of dragon teeth. When making such items, the material used must make sense in the items construction. A winter wolf femur would make a good wand, but would be impossible for a cloak, while its pelt would be vice-versa. Spoils of war drop the item cost in half for crafting magical items.
Alternatively, the item could also add a tiny little thematic bonus. For example, if you used the winter wolf pelt as a cloak of resistance +1, it grants an additional +2 resistance bonus against the first cold save of the day.
Soulstone: When an Abberation, Fey, or Outsider die, they may choose to leave a piece of their soul in a solidified form. If you can find or convince/trick one of these creatures to leave such a boon to you at their death, you can use their soul stone to make magic items. Using soul stones work just as above, but you can use the soul stone in any item, altering its form into whatever you need. A soulstone should always have a tiny thematic bonus, as the above one.
Alternately, the partial soul can be bargained with for temporary boosts of power. Failure to uphold the bargain causes the magic item to loose it's magic powers, until the bargain is completed. (not sure what generic boosts of power might be, maybe it is more appropriate to leave it blank...)
Also alternately, A new magic item slot can be added into the game, specifically for a soulstone. To use a soulstone in this way, you actually force the stone into your body, granting you magical powers while it is imbued in you. It is a full round action to remove or insert a soulstone, and the character is dazed 1 round after one is removed or inserted. The soulstone grants the character a number of spell like abilities. The spell casting stat is depended on the creature that the item was taken from: Aberration is Wisdom, Fey is Charisma, Outsider is Intelligence. The DM decides what spells the soulstone grants. Once a soulstone is made into a magic item, it can never be retrieved to be used like this again. For this rule, I plan to use clerical domains and sorcerer bloodline spells for the bonus spells since they have them grouped together in theme so nicely.
I know this was a lot of text, and the final item was a bit of the opposite of "low magic." Thoughts?