Just a bit of clarification.
crafting does not limit your ability to acquire additional goods.
Normally if you purchase an item that is equal to your wealth level, you have to wait 2 weeks to be able to do so again. With the craft mundane, this restriction is not there.
Also, I’m not sure if your concern with it being extraordinary is bc first are less readily available? Certain extraordinary can be just as easy as some mundane, the difference is the GM, and what they think.
Poisons via extraordinary are probably overall easier.