You purchase them the same as the shares. The current price, say...

You purchase them the same as the shares. The current price, say 10c, is the premium (current intrinsic value) you are paying. The strike is 50c, so they are worthless unless the share value goes above 50c by 31/8/2014. If you buy 10,000 options at 10c, your investment is $1000. Intrinsic value of the option is the difference between the share price and the strike price. If you want 100% return, the share price needs to be around 70c. If you purchased $1000 worth of .35c shares instead of the options, you would also have 100% return. But above 70c share price by Aug 2014 is where the options will start to shine... the return is exponentially higher with the options than if you invested into the shares. Eg, if the share price was at $1, your $1000 worth of .35 shares would be worth approx $2857. Your $1000 worth of options would be worth approx $5000.

These figures are in regards to trading the options themselves. Most people will trade the options instead of converting.