Scorpion venom is the most precious liquid on earth, totaling at $39,000,000 million for a single gallon.
This is because it's only been recently that it's been available for purchase, so there is very limited quantity so there aren't many farmers for it. The quantity is also limited because each scorpion doesn't give any more than 2.0mg (more like 0.5mg on average) for each "milking."
It's also in demand. The venom is needed to produce its anti-venom, and there's a protein found in the venom that can help ease the pain of those with chronic inflammation illnesses.