It's called "caustic potash" and available from chemical supply stores. I just found a local supplier. It's running me $1.79/lb now - in 100 lb bags, out the door, after taxes.
KOH works much, much better for high titration oil. NaOH is fine if your oil is pretty pristine, but for the well-used stuff that I get, KOH is the stuff of choice.
I bought off ebay the 10 lbs also - but the shipping costs almost double the price. The high cost of methanol makes the price of biodiesel higher - but it's still ~1/4 the cost of diesel. Maybe less if you can optimize your usage of methanol.
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