Old Ericssons, Siemens, Nokia, and Motorola - including this beautiful rainbow StarTac: http://lekki.fr/fr/mobile/71-startac-rainbow.html#&panel1-1
$10 to purchase. Throw it away, drop it in the toilet... as long as you can get the sim, no problem. And if, like me, you don't make a lot of cell calls (I have internet phone at home), around $10 a month in prepaid airtime.
Make sure you ask to have the mobile browser turned off because you "accidentally" can get a bunch of charges by the conveniently placed button that starts the browser.
There are different definitions of awesome, but around $150 a year for home and cell service with two phones is mine.