it's a deal
Said when one is amenable to a deal or agreement, especially regarding an acceptable price or exchange for something. A: "Your car needs a lot of repairs, but since you're such a loyal customer, I'm willing to charge you a lower price." B: "Oh wow, it's a deal!"
It's a deal.
Okay.; It is agreed. You want to sell me your stereo for $100? It's a deal. Bill: Let's go to dinner together tonight. Mary: It's a deal.