Amazon has the well-reviewed 2-Pack Craftsman V20 4.0Ah Lithium-Ion Battery (CMCB204-2) for $79 - $10 off coupon (check "Apply $10 coupon") = $69 with free shipping.

Select Craftsman tools & batteries on sale (price after coupon if applies):

• 262-Piece Mechanic Tool Set for $149
• V20 Tire Inflator Air Compressor for $49
• V20 4.5" Angle Grinder (CMCG400B) for $53
• 21-Piece Drill Bit Set/Screwdriver Set for $20
• 12-Piece 1/2" Drive Impact Socket Set for $60
• Cordless Stick Vacuum Kit w/ Battery for $134
• 14-piece CMAM2214 Gold Oxide Drill Bit Set for $9.98
• V20 7-Tool Cordless Combo Kit w/ 2 Batteries & Charger for $239