Downvoted. Exchange does not require a common estimate of "value", although reciprocal altruism probably does. Rational agents will undertake all exchanges which make both of them better off according to each agent's utility function. Assuming TDT, agents which are similar to each other will also reach a Pareto optimum in a bilateral monopoly game.

Humans might sometimes be unable to agree to an exchange in a bilateral monopoly, but that need not imply any disagreement about "value": for instance, they might disagree about bargaining positions, or using brinkmanship to extract concessions from other parties.