One of the best choices for a transmitter battery is the Sanyo Eneloops. They are a NiMh but newer design where the self discharge rate is very low, rivals LiPo. You can charge them this month, put them away and then fly next month without having to recharge. They are available now in most hobby shops and several on-line sources with the connectors of choice attached; just be sure to ask for Eneloops. You can also get them as individual cells from sources such as Amazon.com as 2000 mah AA cells. Again, make sure they are Eneloops.