Hey, As this is relevent thread, I will request all to purchase LiFE battery insted of LiPO for lower voltage.
This is because, I have seen to malfunction some cheap Tx (6 ch, 9 ch.) while you apply voltage more than 11 volt. All 2.5GHz sets are works on 5 volt. So, No Problem.
And yes,
hobbysea is the cheapest at present. (-it's purely relative and changes always).