Well everybody seems to recommend Thunder Power; but I'm the kind of guy that likes to swim against the tide (I didn't buy a Futaba gy401 either) so I just ordered a couple 3200mAh cellpro from FMA direct for a hurricane 550 and some 2200mAh hextronics from Hobby City for a mini titan. The hextronics were a gamble but for $30.00 apiece I figure if only half of them are any good it's a wash.