Contemporary approaches to “non-market accounting” depend critically on methods of “monetization,” i.e., determining prices for goods outside the market. Monetization constitutes a case of economic measurement in a narrow sense that has not yet been analyzed in the literature on measurement in economics. Monetization, I will argue, uses homo economicus—originally created as a model to explain existing prices—as a measuring device, one that generates new prices for goods that are not traded on markets. Homo economicus, though long contested in microeconomics, is thus enjoying a dubious revival in non-market accounting.