Not really, you can use any real (fiat) or virtual (cryptocoin) unit you want, conversion at a given time is always possible, my question was whether the "collection" was sold as a whole (be it 80 Ether or US $ 255,000 or whatever) and bought by a single buyer, or if each whale was sold separately (and then we would have 3,350 buyers) or what?
Ok, if you like it better, "sold for an amount of around 80 Ether valued at the time of the transaction around US $ 255,000 (but the virtual currency is characterized by a high volatility)".
But this doesn't change the question, was it a single buyer, 3,350, or what?
BTW, if the sale happened within 9 hours it smells fishy anyway (to me).