Boxed-Gifts via Amazon offers the Art Lebedev Thermal Battery Mug for $12.99 plus $4.98 for shipping. That's the lowest total price we could find by $4. This ceramic mug features a battery icon with green bars which match liquid levels.
Amazon offers Prime members Calypso Basics 2-Qt. Tea Kettle in Turquoise, model no. 30702, for $23.55 with free shipping. (Non-members can spend $35 or more to bag free shipping; otherwise it adds $6.49.) That's the lowest total price we could find in any color by at least $5. It's designed for use on gas or electric stoves.