As one of its daily deals, That Daily Deal offers the Pilot Electronics 5,200mAh Portable Battery Pack / Heat Pack for $14.99 with free shipping. That's $5 under last week's mention and the lowest price we could find by $25 for any color. It heats up to 120° Fahrenheit and lasts for up to 3.5 hours. Deal ends January 12.
June brings some big deals and sales, but you're better off postponing certain purchases.