Getting a cheap US phone number

After looking at a variety of options, my suggestion is to use a magicJack (link).

magicJack is a USB connector between your phone line & computer. Very easy to set up.  Cost is $19.95 per year and with this you get a dedicated US phone number, voice mail service and most importantly free calls to anyone in the US.  Plug in a headset or just use your computer, simple.

Buy online or whilst in the US for a cheaper option (sells for $49.95 in the US with 1 year fee included).  If you are not heading to the US, expect to pay around double the price for one to be sent to you.