Water off the Steam Clouds
Tabula Rasa, Eternal fires are always more expensive than any other eternals. That is because they are not as easily get by merely mob farming. Normally they can be sold for 40-50 Tabula Rasa gold on the Auction House. Especially engineer farm of steam clouds will bring you a big fortune. To make more Tabula Rasa Gold, you need to farm Crystallized Fire and Crystallized Water off the Steam Clouds in Shoals Basin.