What is Price?

Legal Definition
In ordinary usage, price is the quantity of payment or compensation given by one party to another in return for goods or services.

In modern economies, prices are generally expressed in units of some form of currency. (For commodities, they are expressed as currency per unit weight of the commodity, e.g. euros per kilogram.) Although prices could be quoted as quantities of other goods or services this sort of barter exchange is rarely seen. Prices are sometimes quoted in terms of vouchers such as trading stamps and air miles. In some circumstances, cigarettes have been used as currency, for example in prisons, in times of hyperinflation, and in some places during World War 2. In a black market economy, barter is also relatively common.

In many financial transactions, it is customary to quote prices in other ways. The most obvious example is in pricing a loan, when the cost will be expressed as the percentage rate of interest. The total amount of interest payable depends upon credit risk, the loan amount and the period of the loan. Other examples can be found in pricing financial derivatives and other financial assets. For instance the price of inflation-linked government securities in several countries is quoted as the actual price divided by a factor representing inflation since the security was issued.

Price sometimes refers to the quantity of payment requested by a seller of goods or services, rather than the eventual payment amount. This requested amount is often called the asking price or selling price, while the actual payment may be called the transaction price or traded price. Likewise, the bid price or buying price is the quantity of payment offered by a buyer of goods or services, although this meaning is more common in asset or financial markets than in consumer markets.

Economists sometimes define price more generally as the ratio of the quantities of goods that are exchanged for each other.

Price theory Economic theory asserts that in a free market economy the market price reflects interaction between supply and demand: the price is set so as to equate the quantity being supplied and that being demanded. In turn these quantities are determined by the marginal utility of the asset to different buyers and to different sellers. In reality, the price may be distorted by other factors, such as tax and other government regulations.

When a commodity is for sale at multiple locations, the law of one price is generally believed to hold. This essentially states that the cost difference between the locations cannot be greater than that representing shipping, taxes, other distribution costs and more. In the case of the majority of consumer goods and services, distribution costs are quite a high proportion of the overall price, so the law may not be very useful.
-- Wikipedia
Legal Definition
Contracts. The consideration in money given for the purchase of a thing.

2. There are three requisites to the quality of a price iii order to make a sale.

3. - 1. It must be serious, and such as may be demanded: if, therefore, a person were to sell me an article, and by the agreement, reduced to writing, he were to release me from the payment, the transaction would no longer be a sale, but a gift, Poth. Vente, n. 18.

4. - 2. The second quality of a price is, that the price be certain and determinate; but what may be rendered certain is considered as certain if, therefore, I sell a thing at a price to be fixed by a third person, this is sufficiently certain, provided the third person make a valuation and fix the price. Poth. Vente, n. 23, 24.

5. - 3. The third quality of a price is, that it consists in money, to be paid down, or at a future time, for if it be of any thing else, it will no longer be a price, nor the contract a sale, but exchange or barter. Poth. Vente, n. 30; 16 Toull. n. 147.

6. The true price of a thing is that for which things of a like nature and quality are usually sold in the place where situated, if real property; or in the place where exposed to sale, if personal. Poth. Contr. de Vente, n. 243. The first price or cost of a thing does not always afford a sure criterion of its value. It may have been bought very dear or very cheap. Marsh. Ins. 620, et seq.; Ayliffe's Pand. 447; Merlin, Repert. h. t.; 4 Pick. 179; 8 Pick. 252; 16 Pick. 227.

7. In a declaration in trover it is usual, when the chattel found is a living one, to lay it as of such a price when dead, of such a value. 8 Wentw. Pl. 372, n; 2 Lilly's Ab. 629. Vide Bouv. Inst. Index, h. t.; Adjustment; Inadequacy of price; Pretium offectionis.
-- Bouviers Law Dictionary
Legal Definition
The consideration (usually in money) given for the purchase of a thing. It is true that "price" generally means the sum of money which an article is sold for; but this is simply because property is generally sold for money, not because the word has necessarily such a restricted meaning. Among writers on political economy, who use terms with philosophical accuracy, the word "price" is not always or even generally used as denoting the moneyed equivalent of property sold. They generally treat and regard price as the equivalent or compensation, in whatever form received, for property sold. The Latin word from which "price" is derived sometimes means "reward," "value," "estimation." "equivalent." Hudson Iron Co. v. Alger, 54 N. Y. 177. See Price current.
-- Black's Law Dictionary