America Online Inc is challenging Prodigy Services Co, which just announced plans to charge usage fees for the most heavily-used databases on its viewdata service, by cutting prices to its own 250,000 subscribers: the company says it deliberately waited until after the Prodigy announcement to disclose its new pricing, hoping to maximise attention for its move and woo subscribers away from the IBM Corp-Sears, Roebuck & Co joint venture; under its new plan, subscribers will pay $9.95 a month for five hours of access to all its services, a rate that it claims is less than half the price of Prodigy’s new tariif; extra hours will cost $3.50 each; at Prodigy, subscribers pay $14.95 a month for unlimited access to many of the features but from July 1 will pay surcharges after spending two hours on widely-used bulletin boards.