HomeDepot has this Milwaukee M12 12-Volt Lithium-Ion Battery Pack (2-Batteries) Including 1 M12 XC6 (48-11-2460), and 1 M12 CP3 (48-11-2430) battery for $99. Not sure if this is a real slick deal but in comparison the XC6 battery sells for $119 alone.
https://www.homedepot.c