Beneficial terms of trade exist when prices are set between the two parties':

Beneficial terms of trade occur when prices are established between two parties and are set in a way that reflects their opportunity costs. Opportunity cost represents the value of the next best alternative that is forgone when making a choice. In trade, when each party specializes in producing goods where they have a comparative advantage, they can trade at a price that is more favorable than their respective opportunity costs.

For example, if one party can produce a good at a lower opportunity cost and trades for another good that they would find more expensive to produce themselves, both parties benefit from the trade as long as the trade price falls between their respective opportunity costs. This ensures that each side receives more value from the transaction than what they would have gained from producing the goods on their own.

In contrast, average costs, maximum acceptable prices, and minimum production costs do not account for the trade-offs that each party faces. While these factors may influence pricing, they do not inherently ensure a mutually beneficial trade that maximizes the gains from trading goods based on their opportunity costs.