Best Buy: Lenmar Lithium-Ion Battery for IBM Thinkpad 390, 390E and I1700 Series Laptops LBIT390LX
Amazon.com: Duracell 389/390 Silver Oxide Button Battery, 1 Count Pack, 389/ 390 1.5 Volt Battery, Long-Lasting for Watches, Medical Devices, Calculators, and More : Health & Household