IOWA CITY, IA - Tickets for the championship finals are all that remain for the 2001 NCAA Championships, scheduled for March 15-17 at Carver-Hawkeye Arena in Iowa City, IA.   All-session tickets and a three-session ticket package are all sold out. Due to the single mat configuration for the finals, seats that were not available for the rest of the championships will be added, thus creating the extra tickets.    Tickets for Saturday afternoon's championship finals are $35 and will go on sale Tuesday, January 23 at the University of Iowa Athletic Ticket Office. The ticket office phone number is 1-800-IA-HAWKS.    Sessions are scheduled to start at 11 a.m. and 6:30 p.m. Thursday, at 10 a.m. and 5:30 p.m. Friday and at 8 a.m. and 1 p.m. Saturday. ESPN2 is scheduled to televise the championship finals at 5 p.m. (CT) on Saturday.