Even cheaper, if you want to trade futures, the margin requirements are even lower, $500-1000 minimum, and you can use Ninjatrader as your trading platform for

Even cheaper, if you want to trade futures, the margin requirements are even lower, $500-1000 minimum, and you can use Ninjatrader as your trading platform for certain brokerages. Ninjatrader has a pretty good C# interface to trade with. You have to pay for Ninjatrader if you want to trade, but you can sim trade and write your own trading strategies and backtest for free until you're ready to trade for real.