In April, I was in New York (Mid town) and checking about pre-paid GSM SIM only card.
For some reason, the first two shops (T mobile and Cingular) said that I have to buy the phone as well as part of the pre-paid package. To be honest, when I think back now, I am not sure if I have made clear to them or they understood me correctly.
However, without giving up, I went to another Cingular shop, they happily got me a pre paid SIM. The girl said that usually they charge a connection fee but she is waiving it (some kind of promo must be), and she said I can buy a card in $10, 30 or 50). As she did not have a $10 in stock I bought a $30. That was just great. It is just 10 cents per minute within US, and 15 cents to Canada. I did not check the Australian rate, but I made a couple of short calls. I did not use it heavily, but after two weeks in US, I still had about $15 left in the card.
I was very very pleased as if I did not get this, I would have had to use Roaming, which would have cost me about $1.00 to 2.00 per minute.
Great value. I would strongly recommend.
BTW, GSM is gaining popularity. My phone is a tri-band Nokia 6600. It is worth buying a tri-band as they do not cost much extra nowadays.