What options do I have for batterys in the dx4s? I know spektrum makes a battery to fit but I'm not really up for the $50. Anything from hobbyking fit?

find the dimensions of the spektrum battery and then ck the hobbyking site. I found a Life battery to go in my DXR3 radio there.

I've been combing through HK quite a bit. It's hard to find anything with decent capacity that will fit. On the other hand, I'm getting 37 hours from a set of AA Energizers, so even a lower capacity pack might be okay. Spektrum pack dimensions are 58mm x 60mm x 16mm, btw.