Sharebuilder is a legitimate site, but it's expensive. They have almost no customer complaints. It costs an average of $10 per trade and $25 per year (don't know if that applies just to IRA accounts). They offer plans that save you from paying $4 to buy the trade; it's not worth it. They get very few customer complaints by the BBB. I've contacted them and their customer service 15 months ago was above average in quality. That way you can buy with fractional shares. Like with Fidelity, there's a $50 closeout account fee, as well.
Buying Fractional Shares:
https://www.sharebuilder.com/sharebu..._PSSTR001.aspx
ShareBuilder: Build Your Future
BBB Report:
Better Business Bureau
Fee per Trade
https://www.sharebuilder.com/sharebu..._PSSTR002.aspx
How trading works (it's different)
https://www.sharebuilder.com/sharebu..._PSSTR004.aspx
Full Fee Schedule: https://www.sharebuilder.com/sharebu...s/Default.aspx