hecate essence was an item you could put into your inventory, and it was on auction.
lowest price was 300 for 8 pieces total, second lowest was 4k for 52 pieces total
Reminds me of an idea I talked about a while ago where players could use bottles to bottle the essence up for later use.
hecate essence items coming soon 
300 and 4k drachma 
it would have to be an almost guaranteed drop from any chest to be anywhere near that cheap