Because many of the samples are quite sizable, Mr. Mitchell said it is not feasible to try to carry them in his own luggage. “I just don’t have any other choice. You’ve got to be able to let the client touch it. I have to bring them with me even if it costs $25.”

Jerry Bower, an entrepreneur who recently started a company, Wine Galaxy, that offers wine-of-the-month memberships for corporations to give to employees or clients, said he, too, often travels with more than one bag. “I have to travel quite a bit in order to build relationships,” he said. “I do carry a lot of different literature and presentation pieces, and sometimes wine samples.”

The new fee of $25 for a second bag is being levied by Continental, Delta, Northwest, United and US Airways. The low-fare carrier AirTran has announced that it will charge $10 for a second checked bag. Airlines have long levied fees for checking a third bag. Some carriers have recently increased those as well, and the fees on the major carriers now run as high as $100.

As the airlines struggle to stay in the black, charges for amenities formerly included in the ticket price are on the rise. Depending on the carrier, travelers now can wind up paying extra for everything from food to curbside check-in to bulkhead seats that offer extra legroom.

As for the extra-bag fee, even those who say they pack lightly for their trips foresee problems caused by price-sensitive fliers overfilling their carry-on bags and using large amounts of scarce overhead-bin space.