if lipos are what you are after mb models are selling some for a realllllly good price the c rating is higher the better i believe and as for mah i use 4400 which is plents but more is aslways good
http://www.oople.com/forums/showthread.php?t=94830
mike is a really nice bloke so is ross who works there give them a call they are good for advice and wont sell you somthing you dont need