Aaron, I've been looking around for small 5000 mili-amp packs, and I came across one in a different thread, here on the forum. Might be worth checking it out. Turnigy 4000 mili-amp, which is a little less then you might want, but it's one of the more compact battery packs I've seen. No idea of the quality though. I'm not really a LiPo guy.
http://www.rctruckandconstruction.co...&postcount=107