U.S. Airways said starting July 9, 2009, fliers will be able to pay for checked bags when they check in online for their flights. The first checked bag costs $15, while the second will run you $25. For customers who prefer the traditional method and choose to pay for checked bags at the airport, there will be an additional $5 service fee, US Airways said. Makes you want to reconsider the family vacation transportation mode this summer...