We assume that the decisionmaker can sell the used equipment after paying a transaction cost when he no longer needs it, and that the transaction costs are linear to the price. Our analysis shows that the optimal timing of online algorithm with considering the profit selling used equipment is earlier than that of online algorithm without considering it, and that the real competitive ratio of online algorithm is more than the nominal competitive ratio if the transaction (buying and selling) costs are included in the cost buying the equipment when the decisionmaker designs online algorithm.