Compuserve 72265,3xx from 1981 on TRS-80 Model at 300 baud go $6.00 per hour. EAAsy Sabre EAA5xxx not long after. Looked up many flights and used our local travel agent to book them. Many years later my father invested in a travel agency for the perks. They were on Sabre so I was able to send my online bookings directly to their office.
I still use my ES number for my AA account!