You guys should use Interactive Brokers. A penny a share commission with discounts above 500 shares. $7.75 for 1000 shares. $1 for 100 shares. You cant beat it.
Very good execution and if there is only a partial fill you on pay a partial commission. I switched to them 6 months ago and will not go back.
The interface takes some time to get used to but there are very many powerul features you can take advantage of
Market Data 
Markets 
AI
