Bruce Watson writes at WalletPop, inter alia:

While the $2.1 million that Zhao Danyang paid for a three-hour lunch with Warren Buffett is a ridiculous amount of money, I'm sure that some smartass classics scholar is going to point out that Cleopatra had a more expensive meal at some point.

Ever notice how when you actually do know more than someone about someone, you tend to be labelled a "smartass" ... anyhoo, at the risk of being labelled a smartass, I've always wondered about the expenses of Vitellius' tastes (Suetonius, Vit. 13):

He was chiefly addicted to the vices of luxury and cruelty. He always made three meals a day, sometimes four; breakfast, dinner, and supper, and a drunken revel after all. This load of victuals he could well enough bear, from a custom to which he had enured himself, of frequently vomiting. For these several meals he would make different appointments at the houses of his friends on the same day. None ever entertained him at less expense than four hundred thousand sesterces.1 The most famous was a set entertainment given him by his brother, at which, it is said, there were served up no less than two thousand choice fishes, and seven thousand birds. Yet even this supper he himself outdid, at a feast which he gave upon the first use of a dish which had been made for him, and which, for its extraordinary size, he called " The Shield of Minerva." In this dish there were tossed up together the livers of char-fish, the brains of pheasants and peacocks, with the tongues of flamingos, and the entrails of lampreys, which had been brought in ships of war as far as from the Carpathian Sea, and the Spanish Straits. He was not only a man of an insatiable appetite, but would gratify it likewise at unseasonable times, and with any garbage that came in his way; so that, at a sacrifice, he would snatch from the fire flesh and cakes, and eat them upon the spot. When he travelled, he did the same at the inns upon the road, whether the meat was fresh dressed and hot, or what had been left the day before, and was half-eaten.

... and while looking for an online version of that, I came across this interesting article from the International Journal of Eating Disorders, which someone might want to track down:

Were the Roman Emperors Claudius and Vitellius bulimic?
Paul Crichton *
Maudsley Hospital, London, United Kingdom

*Correspondence to Paul Crichton, Maudsley Hospital, London, United Kingdom

Abstract

Objective
to investigate the eating habits of Romans during the first two centuries A.D. and their attitudes towards these eating habits in the light of contemporary Latin literary and historical sources and influential Greek medical sources. Method: An extensive search of sources on the Roman Empire and emperors in the first two centuries A.D. was carried out. Two historical cases of binging and self-induced vomiting, namely the Emperors Claudius and Vitellius, were identified and described in translated extracts from the original Latin source. Discussion: It is noted that cultural and social factors are important influences on eating habits which would now be considered pathological.