Value in use describes what I have to give up to obtain more of a good. I know I will have to reduce my leisure, consumption, savings or investment to obtain more of something. That is the basic trade-off in value.
Value in exchange describes what I have to trade to obtain more of a good, and describes the opportunities available in the market.
Wealth maximization predicts that a person will choose to obtain the good or service in the place where it is cheapest, where the amount given up is the least. Sometimes, it is cheapest to produce it yourself, and other times, it is cheapest to buy it.
Value is linked to Price through the mechanism of exchange. When an economist observes an exchange, two important value functions are revealed: those of the buyer and seller. Just as the buyer reveals what he is willing to pay for a certain amount of a good, so too does the seller reveal what it costs him to give up the good.
Additional information about value is obtained by the rate at which transactions occur, telling observers the extent to which the purchase of the good has value over time.
Said another way, value is how much a desired object or condition is worth relative to other objects or conditions. Economic values are expressed as "how much" of one desirable condition or commodity will, or would be given up in exchange for some other desired condition or commodity. Among the competing schools of economic theory there are differing metrics for value assessment and the metrics are the subject of a "Theory of Value." Value theories are a large part of the differences and disagreements between the various schools of economic theory.
In classical economics, the value of an object or condition is the amount of discomfort/labor saved through the consumption or use of an object or condition (Labor Theory of Value). Though exchange value is recognized, economic value is not dependent on the existence of a market and price and value are not seen as equal.
In this tradition, to Steve Keen "value" refers to "the innate worth of a commodity, which determines the normal ('equilibrium') ratio at which two commodities exchange. To Keen and the tradition of David Ricardo, this corresponds to the classical concept of long-run cost-determined prices, what Adam Smith called "natural prices" and Karl Marx called "prices of production." It is part of a cost-of-production theory of value and price. Ricardo, but not Keen, used a "labor theory of price" in which a commodity's "innate worth" was the amount of labor needed to produce it.
In another classical tradition, Marx distinguished between the "value in use" (use-value, what a commodity provides to its buyer), "value" (the socially-necessary labour time it embodies), and "exchange value" (how much labor-time the sale of the commodity can claim, Smith's "labor commanded" value). By most interpretations of his labor theory of value, Marx, like Ricardo, developed a "labor theory of price" where the point of analyzing value was to allow the calculation of relative prices. Others see values as part of his sociopolitical interpretation and critique of capitalism and other societies, and deny that it was intended to serve as a category of economics. According to a third interpretation, Marx aimed for a theory of the dynamics of price formation, but did not complete it.
In 1860 John Ruskin published a critique of the economic concept of value from a moral point of view. He entitled the volume Unto This Last, and his central point was this: "It is impossible to conclude, of any given mass of acquired wealth, merely by the fact of its existence, whether it signifies good or evil to the nation in the midst of which it exists. Its real value depends on the moral sign attached to it, just as strictly as that of a mathematical quantity depends on the algebraic sign attached to it. Any given accumulation of commercial wealth may be indicative, on the one hand, of faithful industries, progressive energies, and productive ingenuities: or, on the other, it may be indicative of mortal luxury, merciless tyranny, ruinous chicanery." Gandhi was greatly inspired by Ruskin's book and published a paraphrase of it in 1908.
Economists such as Ludwig von Mises asserted that "value," meaning exchange value, was always the result of subjective value judgements. There was no price of objects or things that could be determined without taking these judgements into account, as manifested by markets. Thus, it was false to say that the economic value of a good was equal to what it cost to produce or to its current replacement cost.
Value in the most basic sense can be referred to as "Real Value" or "Actual Value." This is the measure of worth that is based purely on the utility derived from the consumption of a product or service. Utility derived value allows products or services to be measure on outcome instead of demand or supply theories that have the inherent ability to be manipulated. Illustration: The real value of a book sold to a student who pays $50.00 at the cash register for the text and who earns no additional income from reading the book is essentially zero. However; the real value of the same text purchased in a thrift shop at a price of $0.25 and provides the reader with an insight that allows him or her to earn $100,000.00 in additional income is $100,000.00 or the extended lifetime value earned by the consumer. This is value calculated by actual measurements of ROI instead of production input and or demand vs. supply. No single unit has a fixed value. Value is intrinsically related to the worth derived by the consumer. [Burke(2005)].