If you're going to buy mining shares you'd be better off with CEX.io really. However you'd need to buy at least 8 BTC worth of hashing power to get anything. 0.02598462 BTC right now will buy you a little over 300MH/s so it's pretty spendy.

If you want to have some bitcoin, just buy some and sit on it, and only trade what you feel safe trading with.