I think it resolves as follows: If A can precommit more strongly than B can (and show than he can), the agreed upon price will $10. If B can precommit more strongly than A can (and show that he can), the agreed upon price will be $500,000. If they're sufficiently equal in mental ability to precommit (or neither can credibly show they've precommitted), the agreed upon price will be either $250,005 (if they're superrational) or nonexistent. Has homo economus developed the ability to precommit?