Ask Slashdot: A Cheap US Cellphone Plan With an Unlocked Phone?

metrix007 writes "I am a recent immigrant to the U.S. I am used to going to countries and paying a small amount, say, $30, for a simcard and using it with my unlocked phone. I can't seem to do that in the U.S., where the only options seem to be to buy a phone and buy minutes as I need them such as with Tracfone, or a contract where I pay an amount per month to pay off a phone and a certain amount of minutes. I have a Google Nexus One, which is better than any phone offered on the basic plans from all the cell providers. Is there any way I can use it as a cell phone in the U.S. for about $30-$50/month? It seems a shame to waste it and have to pay for a lesser phone."