Brokers charge a commission to buy and to sell a security.  The buy and sell together are referred to as a “round trip” in the commission world.

The commission prices below are using the free platforms of NinjaTrader, Amp Global and Tradovate.  NinjaTrader and Tradovate offer commission discounts if someone pays to use their lease or purchase platforms.  At the time of this writing, NinjaTrader offers a lease platform for $225 quarterly, while the platform for purchase is four monthly payments of $329 (or a one-time payment of $1099).  After paying for a platform the fees between the two brokers gets closer.  You can see the fees they charge by clicking this NinjaTrader commissions link.  The commissions list at NinjaTrader is referring to one way, not round trip.  Also, make sure that you are looking at the “All In Rates,” so that you are comparing the same rates.  It is important to tell you that, at Amp, the platform that I use allows a user to have a stop loss and take profit option for free.  Not so with NinjaTrader.  If you want to put a stop loss on your order or a take profit you must buy or lease.  Here is a link to the lease and buy options at NinjaTrader.  And here is a link to the Amp Commissions.