Why not go DIY? From all of the decent brands mentioned above does come with quite premium priced no? Say find some decent powerbank case online and coupled it with a protected type of 18650 battery e.g: Keeppower, Panasonic or Samsung SDI or Sanyo, there ya go... But of course price might be slightly cheaper or higher depends on selections, requirements (mAH ratings for battery, protected or non-protected type, brands etc..). Also if you are not those type who are adventurous into D.I.Y, might just go ahead for available brands in the market. Just an opinion...

On Gigabyte's web just states JAPAN cells. NO info on Panasonic or Sanyo etc... How much did you bought it and whereabout?