best battery for cx2.....

[heyjack8]

ok all this battery stuff is kinda confusing my question is this which duralite battery would be my best bet for flying time and not frying my motors or 3 in1...? and could be charged with the stock e-flite charger......also why do some batteries cost so much..? i mean whos gonna pay 70 to 100 bucks for a battery for a cx2....what makes them so much better..than one costing about 30 bucks or so.....

signed: battery confusion