I used an electric tooth brush on my last cell cleaning. it was OK it was small enough to fit in most ball paths between nails.
http://store.irawoodinc.com/orapad400bao.html
14.95 free shipping.
real cheap one $9.99 http://store.comosuperstore.com/069055832936.html
Crest makes some as cheap as 4.99 probably can get at walmart.