Six Flags Fiesta Texas Tickets are on sale! The 1-Day ticket can be purchased at Oak Hills Terrace Front Office with Mary Leija. The cost for the 1-Day ticket is $33.00, CASH ONLY. The 1-Day ticket will be sold Monday - Friday from 8 a.m. to 3 p.m. at the front office. The Six Flags Ticket sales benefit the Northside Education Foundation which provides grants to NISD teachers for innovative programs.