They are a cool but very overpriced fish (IMO). I'd personally much rather have different types of cichlids for a fraction of the price of a datnoid, but that's all personal preference.
Its one of those things where a rareish fish in nature gets overfished for the trade and demand keeps rising causing the price to rise...
But again, how many people are willing to fork over this sort of money for a dat i have no idea, although over here young ones are still quite cheap...