stop buying new nimah or nicad's
if 9.6v is a good price s/hand yeah ok maybe
but me - just go lipo and be done with it
there is the 9.9v life batteries which are a good gap filler between 7.4v & 11.1v lipo's
but on tweaked guns with high rof my 9.9v life's hardly showed any real increase over decent 7.4v lipo's
even a 30c 9.9v life fresh off charge showed very little extra zest compared to my regular 25c & 30c 7.4v's
Stock & mildly tweaked guns yeah - the life fills the lipo gap
but must be a limit on the juice it can supply coz not an amazing boost with higher springs/rof setups
if you seek higher rof then eventually a good neo motor and lipo is way to go
anything else will hold you back