Abstract: A barter transaction system facilitates a barter transaction by determining a monetary compensation amount to compensate a party in a barter transaction when another party in the barter transaction fails to fulfill his/her obligation in the transaction. The barter transaction involves an exchange of a first non-monetary item from a first user with a second non-monetary item from a second user. The barter transaction system determines a compensation amount for compensating the first user based on a monetary value that the second user perceives of the second item. The perceived value is given by the second user and assigned to the second non-monetary item. The barter transaction system also allows the first and second user to negotiate the perceived value until both users agree to the barter transaction.