Newegg has the refurbished
Logitech K750 Wireless Solar Keyboard for $50 - 30% off with coupon code EMCXWVL83
[Exp 2/4] = $35
with free shipping. The first solar powered keyboard, uses ambient light to power itself, can run for three months on a full charge and includes a desktop app that can monitor battery levels, drain alerts and optical placement.