Newegg offers the refurbished Digital2 4,400mAh Portable Battery in Metallic Gold, model no. DP-4400F_MG, for $11. This $11 mail-in rebate cuts it to $0. With $1.99 for shipping, that's tied with our March mention of this battery in a different color and $15 below the lowest total price we could find for a new one. It includes a microUSB to USB cable and features an LED battery status indicator. Rebate expires June 6.
A 90-day warranty is applied, although it's unclear who backs it.