The phrase you are looking for is bargaining chip, not strip. It could be a piece of information with which you gamble, or a poker chip.

***But if you are sticking with 'bargaining strip', it could be your local swap meet.

The term "bargaining chip" is used to describe a circumstance that gives a person or entity an advantage over another in negotiations. For example, the payment of a debt quickly (rather than over a long time) may be a "bargaining chip" in convincing the person who is owed the debt to accept a reduced amount.

Typically land concessions, but it depends on the negotiation in particular.

I believe it is the Bill of Rights, but I am only a student searching for the answer as well.

The types of bargaining in collective bargaining include distributive, cooperative, and productive. Each plays a key role in determining the specific terms and results of the bargaining process.