they are only sold by alledged 'lisence holders' - this is a 150% CON/SCAM, they are purchased from China for $70 + $40 shipping - but you have to pay the lisence holder and patent holder a 'Royalty FEE' to bring them into the country to resell - this makes them very pricey, especailly when the lisence holders are selling on Ebay..
This to me spells CON ARTISTS - DONT WASTE YOUR TIME - Even the patent holder states they are of low quality on Wikipedia under poweriser. If you buy them and you get hurt, its YOUR FAULT.