I finally found the US plug version and it is cheaper than what I found.
$31.25 Eleaf iStick 50W Styled 4400mAh VW VV Variable Wattage / Voltage APV Box Mod (iStick 50W VV/VW Mod, 4400mAh, Black (US)) at m.FastTech.com - FastTech Mobile
Thanks Bobw1951 and I have just placed an order for it...