What is a transaction in which a buyer and seller work out their own terms of exchange?

A transaction in which a buyer and seller work out their own terms of exchange is typically referred to as a private or negotiated transaction. In this scenario, both parties discuss and agree on specific terms such as price, quantity, and delivery conditions without external interference. This type of transaction allows for flexibility and customization to meet the unique needs of both the buyer and seller. It is commonly seen in various markets, including real estate, art, and certain goods and services.