"Reached an agreement/reached a deal" would express that. I am dealing with that portion of your question, the rest I will leave to others.
In a colloquial way, and with focus on the hard work of the discussion, litigation, etc to form or produce the agreement, you can say that "an agreement was hammed out between A and B" (where A and B can be two people, parties, nations etc)
But, back to the crux. Here one example from the People Magazine:At the moment Sarah's future is unclear. Solicitors undoubtedly will need weeks or months to hammer out an agreement between her and Andrew. She reportedly has a mountain of overdrafts, and the two must decide who will be responsible for her debts. "There will be a financial settlement on her, so she would never have to worry about anything," says a British writer who has studied the royal family. "I would think that she would probably be required to sign a quite rigid contract that she wouldn't divulge any secrets she's been privy to while she has been a member of the royal family—she couldn't write her memoirs."http://www.people.com/people/archive/ar ... 17,00.html
The "will need weeks or months to hammer out an agreement between her and Andrew."
part, focus on the works. And the one with "there will be a financial settlement on her...
" focuses on the fact itself.
I don´t know if one expression with "bargain" in it would be welcome (or polite) in such hour. Anyway, to certain cases would express the truth!