Dallas--Sabre Holdings Corp., the reservation service set to be spun off from parent American Airlines, has unveiled plans to create an Internet b-to-b marketplace for the travel industry. The company said it would use software from Ariba, Sunnyvale, Calif., to create Sabre e-Marketplace, scheduled for launch Oct. 1. Sabre said it would invite other reservation companies and airlines to join the service, which is designed to trim the cost of purchasing supplies used to run travel businesses. If successful in establishing partnerships, Sabre e-Marketplace might be able to use the collective buying power of a number of travel companies to negotiate lower prices for these supplies. The advent of Sabre e-Marketplace underscores the rapid emergence of buying consortiums in American industry, and follows similar efforts in such areas as automotive, health care, aircraft manufacturing and steel.