Real Dictionary

bargain
countable noun: A bargain is an agreement, especially a formal business agreement, in which two people or groups agree what each of them will do, pay, or receive.
countable noun: Something that is a bargain is good value for money, usually because it has been sold at a lower price than normal.
verb: When people bargain with each other, they discuss what each of them will do, pay, or receive.

bargain in American English
a mutual agreement or contract in which the parties settle on what should be given or done by each
noun: an advantageous purchase, esp. one acquired at less than the usual cost