Consumer surplus, opportunity costs
There is a concept in political economy that even neoliberal Economists acknowledge which is that of "consumer surplus", which is the difference between the highest price that a consumer would pay for a commodity, and the prices actually paid. The highest price that a consumer would pay for a commodity is in effect its value to the consumer, expressed in money.
Neoliberal Economists are very fond of using consumer surplus arguments when claiming that technology is substantially improving the living standards of consumers, for example that "free" internet services are worth £19,560 per year to consumers.
But it is not a popular topic otherwise because the claim by Karl Marx that employees are exploited is that employers enjoy consumer surplus from their work. Consumer surplus is a good topic when the consumers are the employees, but not a good topic when the consumers are the employers.
However consumer surplus is very important to understand how the modern political economies have evolved and what drives the living standards in them:
Currently in modern economies agriculture accounts for a couple percent of GDP and manufacturing a couple dozen percent of GDP, yet they comprise the largest part of the living standards of the people.
Agriculture developed in such a way to generate a massive consumer surplus, as intensive cultivation developed thanks to better practices, use of fertilizers, and use of machinery, as prices of food fell way below the maximum prices consumers would have paid and did pay in earlier times.
Industry (including manufacturing and transportation) developed in such a way to generate a massive consumer surplus, as standardized production with machines became common, and actual prices of products fell way below the maximum prices consumers would have paid and did pay in earlier times.
In both the cases of agriculture and industry the enormous consumer surplus was the result of much cheaper fuels, coal and oil/gas: the prices paid by consumers for both are way, way lower than the maximum price consumers would pay for the amount and density of the energy they contain.
Note: The huge consumer surplus of agriculture allows a large number of workers to do manufacturing, and the even bigger consumer surplus of manufacturing allows most workers to do services, which don't have a huge consumer surplus, as they mostly performed by humans powered by farmed food and not by machines powered by mineral fuels.
The replacement of food-powered humans and animals with fuels-powered machines was the essence of the industrial revolution.
The enormous consumer surplus of mineral fuels is easy to miss because not only consumer surplus is somewhat politically dangerous as a concept because it is part of the theory of exploitation of Karl Marx, but also because unlike observed prices and quantities, it is a notional quantity, being the difference between notional maximum price and the observed price.
There is something similar in political economy studies, and it is "opportunity cost", that is the difference between the actual advantage of doing something and the potential advantage of doing something more valuable.
Opportunity costs can be temporal, if the potentially more advantageous action is for the same thing but at a different time, or spatial, if it is for a different thing at the same time.
Usually the notion of opportunity cost is applied to investment rather than consumption: for example a temporal case is investing some funds now in an activity rather than later at a potentially more profitable time. Opportunity costs are as a rule notional too, because it if the difference between an actual advantage and a notional one.
In a sense it is as to revenues the complement to consumer surplus as to costs. There is a considerable amount of opportunity costs, both temporal and spatial as to mineral fuels, which as a rule are limited in quantity: how fast to deplete them (temporal) and whether to use them for generating motive power, generating heat, or as chemical feedstock. These opportunity costs can also be very large, even if perhaps not as large as the consumer surplus of mineral fuels, and perhaps in the future there will be a lot of regreat that the rate of consumption of mineral fuels has been too high so far, or that too much of them have been burned up just to generate heat, or for transportation.
Opportunity costs and consumer surplus are very important for understanding the actual evolution of political economies and for policy making.
Note: both are notional quantities and similar in that the physics concept of "potential energy", that however is a simplifying and somewhat misleading concept.