netwire, I can not PM you (free account) but I already know TD Ameritrade is one of the best flat fee brokers. However, when they are short or something, they don't care about you like now they have restricted PAIM buys while everyone else is trading it. That's why I need a backup broker or maybe more to be in control of my trading. I say go with TD Ameritrade ($9.99 per trade) but be ready with a backup. You don't even need to cancel your current Scottrade, keep it and use it when it's better (i.e. for trades that won't cost you extra commission).
Other flat fee brokers are ChocieTrade ($5 per trade) (still restricting PAIM), eTrade ($12.99 per trade), and probably TradeKing ($4.95 per trade) but not sure if TradeKing is flat fee. It's a trade off between lower commission and more "luxurious" trading experience. You choose.
Happy trading.
Your money, your decisions.