Genuine Original Nikon EN-EL9A Battery for Nikon D60 D40 D40X D5000 D3000 MH-23 | eBay
Amazon.com : BIG MIKE'S ELECTRONICS BM Premium 2 Pack of EN-EL9, EN-EL9A Batteries and Battery Charger for Nikon D5000, D3000, D60, D40x & D40 Digital SLR Camera : Electronics
Nikon D5000 Battery Door Replacement - iFixit Repair Guide