chubbiestech via eBay offers the used Motorola DROID 2 3G CDMA Smartphone for $39.99 + get free shipping.  This is the best price we have seen for this former flagship phone from Verizon's popular DROID line, with a clean ESN.  Note that this is a CDMA phone that will not work on GSM carriers.  Item is listed as in good condition.

Note that it is also available in white in similar condition for $5 more.

Motorola DROID 2 features include a 3.7-inch 480x854 color touchscreen, 5-MP camera with auto focus, slide-out QWERTY keyboard, virtual QWERTY keyboard with Swype,  720p video capture, 8GB of internal memory microSD slot, WiFi connectivity, 3G mobile hotspot capability (with support for up to five devices), Bluetooth, Android 2.2 OS, up to 9.5 hours of talk time, and more.