The Stratux power input is a USB Micro port, like most Android phones use. Many folks have these cables already because the port is very common. If you need a cable, they are easy to find in the $2 - $10 range (like these).
Power can be provided either by a battery (like this one) or by a cigarette lighter adapter (like this one). Many folks have one or the other (or both) already available for use with other devices.