Make sure you do your due diligence with any of the smaller firms. Check who they clear through, and take a look at the NFA website for any other problems the firm may have.
IB certainly has problems, but they are rock solid financially, conservative in their trading policies (high margins), and you can trade just about anything from one acct.
I know that Velocity has been advertising that they still have $500 E mini daytrade margins if that is what you are looking for. Good luck surviving for more than a few days if you actually leverage yourself to this degree however. Anyway, they seem to have good reviews in the broker section here on ET.
Jay