i suppose you are not aware of tatkal charges and tatkal booking procedure. Tatkal charges in addition to normal fare per passenger( applicable both in peak and lean periods )
10 %of the basic fare for second class and 30% of the basic fare for second class and 30% of the basic fare for all other classes subject to minimum and maximum as noted below:-
(In Rupees)
Second(sitting)...
more... min 10:00 max 15:00
Sleeper min 75:00 max 150:00
AC Chair Car min 75:00 max 150:00
AC 3 Tier min 200:00 max 300:00
AC 2 Tier min 200:00 max 300:00
Executive min 200:00 max 300:00
and if you are relying on your internet connection to book a tatkal ticket then beware, you may end up getting a WL ticket within minutes of booking opens at 8am. so suggest you to go to nearest PRS (railways station reservation counter)
follow the rules here
/faq/post/152