Do a calculation for zeroda v/s RK global for 1 crore and you will arrive at the following:
Actually for zeroda per lot brokerage comes to around 6 Rs per lot if you trade nifty of 1 crore and for RKG it comes to Rs.9 per lot and savings you get in zeroda is 3Rs per lot + 10% more margin + if you use CO then with all its drawbacks you get double as compared to RKG
Other benefits in zeroda is that software is free and RKG charges 100Rs per segment per month for web and for software 300Rs per month per segment
So, zeroda is cheaper but not as cheaper as it appears to be.