what something costs: the payment given in exchange for it, and so also the sum that measures its worth
This word belongs to the marketplace. Solomon's traders bring horses up from Egypt at a price, the survivors in ruined Jerusalem have to pay for the wood they burn, and a flock of goats adds up to enough to buy a field. What the word names is the sum that changes hands, not the silver it is counted out in (כֶּסֶף) and not the pay a worker earns for a day's labor (שָׂכָר).
From there it reaches naturally to what a thing is worth even when nobody can actually pay it. Job says silver cannot be weighed out as the price of wisdom, and the point is not that wisdom is expensive but that it is not for sale at all. The same logic drives the proverb that asks why a fool is holding purchase money to buy wisdom when he has no sense to buy it with.
The most striking uses are the negative ones, where "without price" means simply "free of charge":
- the thirsty are told to come and buy wine and milk with no money and no price
- God hands Judah's treasures over as loot and gets nothing at all for them
- Cyrus is stirred up to rebuild the city and free the exiles, neither paid nor bribed to do it
In each case the absence of a price is the whole point.
The word can also name the fee paid to a person for what they do, and in that use it usually turns sour: priests who will only teach for a fee, prophets who divine for silver, and earnings barred from ever entering God's house. Set against all of that is David at Araunah's threshing floor, refusing the gift of the land and insisting on paying full price, because he will not offer God something that cost him nothing.