You are trolling if you are not using essences and actions in Delubrum

[Fawkes]

It's called the marketboard

They meant trade the ones you already have for ones you need. Buying them off the marketboard doesn't guarantee it will appraise into the essence you actually want.

And with the prices of fragments you could easily spend half a million gil and not even get one of the type of essence you wanted, so it's not really a viable solution.