Worth picking up if your Shark robot vacuum's runtime has started dropping off, since a worn battery is usually the culprit; it's $2.23 off the list price at Walmart. Buy Now at Walmart

Solar charging is worth setting up if your doorbell sits in direct sunlight and you're tired of unclipping the battery to recharge it every few weeks; this one's priced the same as list at $40, so there's no discount here, just standard cost for the convenience. Buy Now at Best Buy