Airplane resevation a problem?

I will be arriving at Delhi in the morning and need to be in Bombay the next morning at the latest, but preferably the same day.
Can anyone tell me if it will be a problem to get a cheap air ticket in the airport, or should one try to reserve from home? How many flights a day between these to destinations - could be a lot, I guess.
Thanks for any answers

http://indian-airlines.nic.in/schedule/default.htm
Day Schedule
From DELHI to MUMBAI
(03/Jan/2004 - Saturday)

Flight No. Aircraft
type No. of
Stopovers Origin Departure
Time Destination Arrival
Time

IC657 A-320 0 DELHI 0600 MUMBAI 0755
IC688 A-320 0 DELHI 0700 MUMBAI 0855
IC165 A-320 0 DELHI 0800 MUMBAI 0955
IC167 A-320 0 DELHI 0900 MUMBAI 1055
IC865 A-320 0 DELHI 1200 MUMBAI 1355
IC887 A-320 0 DELHI 1300 MUMBAI 1455
IC863 A-320 0 DELHI 1700 MUMBAI 1855
IC805 A-320 0 DELHI 1800 MUMBAI 1955
IC810 A-320 0 DELHI 1900 MUMBAI 2055
IC602 A-320 0 DELHI 2000 MUMBAI 2155

Thanks for the info. It made me check out for other airlines servicing this route, and I found Sahara Air, with this homepage:
http://www.airsahara.net/airsahara/index.jsp