Hmm, if you plan to run 2 2s packs in series I would buy this lipo charger:
http://www.hobbycity.com/hobbycity/s...Charge_Capable
It will charge at about 1.8amps, and will do 2 2s packs at once. Plenty for the size packs we are talking about. I have one and it works great, charges each cell in the pack separately, so the charge time is fast even with an out of balance pack.
They also have a 5 amp power supply for 10 bucks.
And 2 of these packs:
http://www.hobbycity.com/hobbycity/s...0mAh_2S1P_20C_
Run them in parallel for a 3200 mah 2s setup that will do 30 and have great runtime, or go in series for a 1600mah 4s setup that should easily beat 50.
With std shipping you are at less than 75 bucks... And I am sure that the prices will come down on the minis, so I can imagine you could keep the cost under 300 bucks for the whole deal...