Rules for Acquiring, Cultivating, or Creating Reagents

Acquiring Reagents
Most magic items have a base cost in either silver or drams of reagents. A dram or reagent normally costs one silver piece barring unusual market fctors. Creators of magic items don’t literally sacrifice a pile of coins (usually). They are using eye of newt, mandrake root, and a variety of other exotic ingredients or materials. These materials are collectively reagents.

Finding Potion Ingredients or Scroll Materials

Canvassing an area for magical reagents requires a week of work to make a roll. Roll Perception + Hearth Wisdom or Pecerption + Alchemy or Perception + Spellcraft, whichever is higher to find potion ingredients, base difficulty 6.
Finding Reagents for disposable magical items such as scrolls and potions is usually easiest in wild lush areas. The difficulty of six assumes a a robustly rugged wooded area that is relatively isolated. Relatively sparsely vegetated areas have a higher base difficulty. Highly cultivated rural areas also have a higher difficulty.
If another regent hunter was in the area recently, the difficulty for the next regent hunter is raised by +1 for every two successes his predecessor rolled since the easy pickings were already claimed.
If the hunter for Reagents is not a spell-caster themselves they have to have to have the Arcana or Alchemy knowledge and also have Hearth Wisdom. Roll Perception + whatever the lowest of their two traits is.
Each success normally yields 25 drams of Reagents. Some areas are saturated with magical power. In such places, each success rolled can yield 50-100 drams of Reagents. Areas like this are nearly always claimed by powerful beings, be they politically powerful or magically powerful or both. Someone will probably notice you poaching reagents from their territory.
A sedentary character with the proper knowledge and a lot of time on her hands can cultivate Reagents in gardens or groves. A manager of such static resources typically rolls Intelligence + Hearth Wisdom once per month yielding 200 silver pieces worth of Reagents per success under normal circumstances. Many Reagents bought from a magic suppliers in large towns were generated this way.
Reagents used for making potions and inks usually have a shelf life, but it's not worth the game master's or player's time to worry about it. Just assume that the characters are taking proper precautions to preserve their stores and rotate their stock.

Finding Reagents for permanent magical items, aka durable Reagents

Canvassing an area for durable reagents requires a week of work to make a roll. Roll Perception + or Alchemy or Spellcraft, whichever is higher to find potion ingredients, base difficulty 6.
Finding durable reagents for permanent magical items such as swords or shield is usually easiest in mineral rich areas unless the magical item in question is made of wood in which case forests are the default place to look.
If another regent hunter was in the area recently, the difficulty for the next regent hunter is raised by +1 for every two successes his predecessor rolled, the easy pickings were already claimed.
If the hunter for Reagents is not a spell-caster themselves they have to have to have the Arcana or Alchemy knowledge and also have Hearth Wisdom. Roll Perception + whatever the lowest of their two traits is.
Each success normally yields 10 drams of reagents. Some areas are saturated with magical power. Each success rolled can yield 30-50 drams of reagents. Areas like this are nearly always claimed by powerful beings. Someone will probably notice you poaching Reagents from their territory.
A sedentary character with knowledge of alchemy and a very expensive laboratory can process metals and other minerals to make durable reagents. This is the closest a person can normally get to sacrificing a pile of coins to make a magic item.
A manager of such static resources typically rolls Intelligence + Alchemy once per month yielding 300 drams of Reagents per success under normal circumstances. This 300 dram per success is only after fronting 500 silver pieces worth of raw materials just to make the attempt. Many reagents bought from a magic supplier in town were generated this way.
Stealing, Trading or Borrowing Reagents
Most spell-casters are narrowly focused on a small amount of magical items. There is not a lot of overlap between making potions of Healing and potions of Augmentation. Unless the two individuals were trying to create very similar magic items, assume only 50% of another person’s reagents are useable if you are dealing with two divine casters or two arcane casters and only about 30% of another person’s reagents are useful if an arcane caster is trying to use a divine caster’s reagents or vice versa.
Scroll scribing is pretty universal, you need fancy ink and paper. Worst case scenario, you lose 20% of the value of a set of reagents transferring owners.
Durable reagents are usually easily transferable but not all reagents can be used for all magical items. The hairs of a unicorn are great for items of healing of defense but are unsuitable for being used with most magic weapons.
Assume someone who makes a trade by being a magical supplier does not have this problem as they are accustomed to getting varied clients exactly what they need, assuming they are a competent seneschal or have such a person on their payroll.

Reagents from Magical Creatures

Reagents can be harvested from magical creatures at the Game Masters discretion. In many cases, how the reagents are harvested is just as important as what creature the reagents are being harvested from. Hair from a living unicorn willingly donated is much more magically potent than hair from a dead unicorn, but a dead unicorn yields much more hairs than a living one.
Ethical issues aside, it is more efficient to harvest reagents from magical creatures slain on auspicious times and slain by ritualistic means as opposed to slain at random times though this is easier said than done. If a dangeorus magical beast is attacking, most people aren't going to worry about ritualistic hunting and they will just take down the threat and harvest what they can afterwards.
Characters need to have the rare abilities of Spellcraft, Alchemy, or Arcana to be able to successfully harvest reagents from living or dead creatures.