a couple of us a few years ago at the airfield had a tin foil hat moment of theory.
there cant be that many lipo manufacturers out there. we came up with the conclusion that battery retailers pay a premium per say to come in and skim over the batteries in pecking order. those who pay the premium get to pick what they want for batteries (best i.r. tightest balance between cells) then it goes down the food chain and the left overs go to hobbyking / hobbycity. they then take them to their production facility and put their quality of tabs, wires, tubes etc etc from there which is quality and price based as well. we believed thunderpowerrc goes in as one of the top 2 and then charge appropriate prices for their premium pecking order.
cant prove it but it sure made sense when we were theory crafting while waiting for batteries to charge between flights