"USD 50" means the stock trading at $50 (US dollars), and "USD 2" means the stock trading at $2 (US dollars) in your example. By the way, the commission rate is not $0.0005/share, it is $0.005/share (i.e., half a cent per share).
Cybertrader has platform fees as high as $249 per month. Platform fees aside, Cybertraderâs per share commission is only favorable vs. IB for trades greater than 3,000 shares.