What is the absolute cheapest way to get a Raspberry Pi-style board, which has WiFi, and the ability to provide constant power using solar or other renewable means? Or even just a really long-lasting battery rather than even renewable energy? I am looking for links to products that I can buy 1. Board 2. WiFi 3. Power source By the way, the WiFi chip must have the ability to run a relay... i.e. to be used to receive WiFi from a hotspot, and also to be used as a hotspot itself at the same time. The device needs to do very little other than receive a WiFi connection and then repeat it in a relay-style, i.e. create a mobile hotspot.