Would you buy a peripheral – for the purposes of training yourself to be a better gamer – that gives you feedback in the form of an electric shock? If the answer to that question is "yes," then you might be interested in the $249 Foc.us, "a tDCS [transcranial Direct Current Stimulation] headset for gamers" that allows users to "overclock your brain to increase the plasticity." The Foc.us comes with an iOS app so that the headset "can be controlled manually using the touch sensor."
The company that makes the device acknowledges that the headset is not a medical device and is not regulated by the FDA. While the company claims the device has passed all regulated safety standards, it does warn anyone who suffers from epilepsy or has "implants" not to use the device.
You can learn more about the device here.
We are not sure about the validity of the company's claims that this device will somehow improve your performance using the method it uses, but it does seem mildly dangerous (it probably isn't but I am a bit of a skeptic in all things). It reminds me of the time machine bought off the Internet in Napoleon Dynamite…