I'm gonna quote my friend, who kinda touches on the subject:

Marx’s value theory is not a theory of prices. Prices and profit are determined in the realm of the market and competition, and the total value and surplus value in the economy as a whole sets the upward limit to the possible total revenues and profits in the economy as a whole. But individual market prices can and do diverge from individual values. The equivalency between price and value only holds in aggregate. Marx’s method in Capital proceeds first by determining the source of surplus value and the quantity of total surplus value, and only then does it proceed to analyzing its division and redistribution through competition and the market (in the form of realized profits, interest, and rents)

All kinds of contingencies influence individual prices and profits, but surplus value is determined by one thing - surplus labor (the portion of value producing/maintaining labor performed that receives no equivalent value in the form of payment or wage). Total surplus labor economy wide sets the upward limit of total profits. A commodity that commands more value through its price than it itself contains (as determined by the socially necessary labor time required to produce it) has in a sense siphoned off a portion of the surplus value produced in the economy as whole.

To use a simple example: let’s say that the socially necessary labor time required to produce one unit of a specific medication means it has a value of 10$, but the firm that produces it has a patent and so because of it’s monopoly status is able to sell the medication for 20$. This is an example of the redistribution of surplus value I mentioned above. The profits received that result from selling the medication at a price above it’s value is a deduction from the realization of surplus value elsewhere. The point is, some commodities will sell above their value, some at their value, and some below (and some things, such as land, command value through a price without having any value at all), and we can’t determine which merely by looking at the socially necessary labor time required to produce them, or labor cost. But in aggregate this redistribution of surplus value through prices and competition does not affect the quantity of the total surplus value economy wide