400-500e imo, this can be used outpost so definitely more than any normal everlasting tonic
have seen ppl in-game struggle to get over 350e for Yuletide / Transmogrifier.
If spamming around in Kamadan for a long time is the point, u might get 400e+. saw one earlier today with b/o 450e negotiable, he had c/o 240e.