I actually started using Freetrade which is a division of Ameritrade.. Im a day trader, but very rarely do I scalp.. but your comments about 'real' stocks makes alot of sense because if you are a true scalper who is looking for .05-.10 hits on 5000 shares- it would obviously cost you more in commissions via IB compared to Freetrade, but the reality is that you would never get the fills/speed of execution you need with Freetrade to really pull that off effectively and you cant overlook this. Thats why I think someone who is looking to cut commissions costs needs to decide just how their particular style of trading will fit in with the broker.
I tend to take a position and attempt to hold it for sometimes several hours depending on if the 'plan' is coming together for me so instant execution/slippage really doesnt matter much to me.. but I average about 8 (16 round trip) trades a day- and even with a reduced rate via my old Ameritrade account, I was still paying $8 a trade so my savings with Freetrade actually pay a good portion of my monthly bills.. Amazing when you think about it..
Took me a good 8 months to switch to them because I was afraid it was too good to be true. : )
Market Data 
Markets 
AI
