This paper takes a fresh look at an economic calculation device vital to actions and investments in various markets, the price index. Despite its importance, the price index has been surprisingly overlooked in previous studies in the sociology of market devices and financial instruments. In economics and in the history of economic thought, however, there is substantial amount of intellectual work concerning the construction of index numbers, desirable characteristics of index numbers and the relationship between index numbers and economic theory. To overcome this gap, this paper zooms in on the construction of a basket of price indexes on the one hand, and on the application of this basket in the processes of standardizing calculations in the market for procured public transport in Sweden, on the other. As such, the paper contributes with new knowledge to the sociology of market devices by providing conceptualizations of the price index as a device to standardize calculations and thereby levelling out the market conditions, which are, as it were, understood as necessary for constructing procurability.