Since the parties stipulated the creditor had a written agreement with the debtor permitting it to recover interest, attorney fees, and costs and the value of the creditor's collateral exceeded the amount of its claim, the only factor considered was whether the creditor's attorney fees and costs were reasonable. As nothing in the record demonstrated the necessity of the services of the creditor's expert, the expert's compensation and expenses, as well as the attorney fees incurred in dealing with the expert, were excluded from the creditor's award. With one small agreed-upon exception, interest and the creditor's remaining attorney fees and costs were allowed