Coffee Mug Warmer $20

This KitCheck Shop Coffee Mug Warmer drops from $24.99 to $19.99 at Amazon for Prime members. You can't see a big price drop, but it was $40 around the October Prime sale. This isn't the lowest-priced coffee mug warmer, but it's one of the top-selling coffee warmers at Amazon because it has good reviews and extra features like multiple temperature settings and a timer function. Shipping is free with Prime or when you spend $35. Otherwise, it adds $6.99.