This mobile phone lets you use 2 SIM cards at the same time (both can be on standby at the same time, you don't have to choose one or the other). Slightly cheaper than the other one they started selling (this one is $55.50).
Other specs: Bluetooth, 2.2" touchscreen, tri-band, micro SD slot, FM radio, 2nd spare battery, charges through USB cable.
If you haven't heard of DealExtreme before, check out previous threads - many people here have bought stuff from them. They ship it directly from Hong Kong for free.