Just in case, I don't understand rechargeable lights that want be connected to the computer via a USB port. In my mind, a muddy / dusty light has no business near my computer!
Any electronics store will sell a "power block" that allows you to plug a device with a USB charger into an ordinary wall socket. I use them for all sorts of things....phones, lights, MP3 players.... Don't rule out a light just because of its charger.