Aus Revisionist View of Roman Money, aus: Rome's Imperial Economy, S. 225-6
"Many Roman texts seem to suggest that there is something wrong with the conventional account, and these texts all fit together. How did Cicero transfer the 3 1⁄2 million sesterces he paid for his famous house on the Palatine (Fam. 5.6.2—this was by no means the largest property price we know of in the j classical city of Rome), at a time when Rome had practically no gold coinage? It seems singularly unlikely that his slaves counted out and loaded 3 1⁄2 tons of silver coins and transported this cargo through the streets of Rome (not that Roman ideas of inconvenience were necessarily the same as ours). When a certain C. Albanius bought an estate from a certain C. Pilius for 11 1⁄2 million sesterces (Cic. Att. 13.31.4), did he physically send him this sum in silver coins?
Without much doubt, these were at least for the most part paper, or rather documentary, transactions (the crucial documents will have been waxed tablets). The common- est procedure for large property purchases in this period was probably the one casually alluded to by Cicero elsewhere: a Roman knight becomes enamoured of a certain property at Syracuse, and ‘nomina facit, negotium conficit’, ‘he provides the credits [or ‘‘bonds’’ ], <and so> completes the purchase’ (De off. 3.59).14 This practice is reflected in Cicero’s letters.
And when in Pro Caecina Aebutius’ bid for a rural property being sold at auction is successful, he concludes the affair by ‘promising money to the argentarius’, the banker (Caec. 16), and about that at least there was nothing in the least irregular: no one denied that the property had really been sold—the only question about the sale was whether Aebutius was acting for someone else. And you might buy in instalments: when Cicero bought out the share of the horti Cluviani that had gone to another legatee (Att. 13.46.3), he did so in three payments spread out over nearly a year (Att. 16.2.1), in effect taking a loan from the seller. None of which is to deny that coins might sometimes play considerable roles in major property transactions (see below)."
Entsprechend dem Kaufpreis Cicero wären das also ca 80 Super-Luxushäuschen.