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