TechJoint posted about some of the coolest and most innovative inventions out there. Here are some pretty clever invention you can buy on Amazon forĀ under $30. Playbulb CandleĀ costĀ $18.97. Hydaway BottleĀ costĀ $14.95. Kinsa Smart ThermometerĀ costĀ $14.46. Pocket TripodĀ cost $25. Mynt Smart TrackerĀ cost $19.99. Watch the video below to learn more about the products.