Well, I seem to be able to find hyperion 5i chargers used for about 30-50 bucks. A balancer such as the equinox would be around 20 bucks. Figure about 10 bucks for tap adapters.
For lipos, try this out:
proteck 4000 20c 2s lipo
So, I figure a pair of those lipos, charger and balancer can be done for under 200. Plus you can wire the packs in series during charging, so both can be charged at the same time. Not bad, IMO, and should be able to outdo any nimh, 20c = 80amps, even if they are 15c lipos that is still almost twice what a great nimh can output.