It is sometimes called a 'steal', or a 'find'.
A deal or too good to be true as in a rip off.
In large outlets they would be called "loss leaders."
If a person breaks a valid contact or does not live up to the end of the bargain, then it is called Breach of Contract.
a whale of a seal
the bargain between them was that the lord would grant the vassal land in exchange for military service.MoreThis bargain was done in what was called the commendation ceremony.There is a link below to an article where more information can be found.
Sometimes they are called cavies or GP for short.
it is called diffusion or sometime called borrowing
yankees
They were called unions
As a verb: I had to bargain with the shopkeeper. As a noun: This thing that I bought was a bargain.
This is not an idiom because it means just what it says. If something is a bargain, then it is always a bargain. It doesn't matter what the circumstances are.
Sentences with the word bargain: Noun: The secondhand table was a real bargain. Verb: He bargained with the city council to rent the stadium. No, bargain can not be an adverb.
In general, it's called a compromise. In law, it's called a plea bargain.