Amazon.com: DC 3.7V 2100mAh 804050 li-ion Lithium Ion Polymer Battery Replacement for DIY 3.7-5V Electronic Product, Mobile Energy Storage Power Supply : Electronics
Amazon.com: DC 3.7V 3000mAh 103665 Rechargeable Lithium Polymer Replacement Battery for DIY 3.7-5V Electronic Product, Mobile Energy Storage Power Supply : Electronics
Li-Polymer Battery 3.7V 1500mAh
Lithium Ion Polymer Battery Ideal For Feathers - 3.7V 400mAh : ID 3898 : $6.95 : Adafruit Industries, Unique & fun DIY electronics and kits