You are comparing apples and eggs. The E-Bay ones are Sub-C size while the Component Shop are D-size. This gives me a few doubts as to the real
capacity of the E-Bay ones. Component Shop's highest capacity Sub-C pack is 4600mAH and as far as I know there aren't any higher-capacity cells of this size generally available (yet?). A sudden 50% increase in capacity would be a helluva leap in the technology - unprecedented, in fact.
As far as buying stuff on E-Bay from Far East suppliers, mmmmmmmmmmmm..... We've been told by several Chinese manufacturers that they'll print any old thing on a label to order (yep - CE symbols - the lot!). Funny then - if it's that easy then why can't I see either Tamiya or Kyosho on these cells anywhere - just in the tagline for the sales pitch? I can
see a figure which I don't trust.
Ever heard of the "Super Power Battery Co Ltd"? Me neither. Wanna risk it? Go ahead; it's your money (not mine).
Makes you wonder though, dunnit?