Poisoner (2 SP)

You can coat a weapon or up to three pieces of ammunition in poison (see Useful Items in Combat) as a free interaction instead of an action. In addition, you can craft a poison in half the usual amount of time (see Crafting), and any poison you create or poisonous spell you cast ignores resistance against poison damage (see Resistance and Vulnerability).

For even cheaper poison, consider the Inflict Disease spell.