I was less than amused by our local biodiesel supplier. A year ago, my brother looked into buying it 500 gallons at a time for his above ground fuel tank.
They quoted a price of $2.60 when petro-diesel was only about $2.
So, when the petro price skyrocketed, we looked back at the bio price and said "YES! Now is the time!"
Wrong. When our petro-diesel price hit $3.49, the bio-diesel price hit $3.85. Supply and demand wasn't the issue - keeping the price above petro and maximizing profit was - at least with this company. Don't know about any others.