Logitech has a subsidiary called Ultimate Ears, or UE for short. This subsidiary makes all sorts of Bluetooth speakers, but mostly specializes in 360-degree speakers like the UE Boom and UE Boom 2. They also have the UE Roll which is their cheapest Bluetooth speaker, but also the most impressive. It's a rather small Bluetooth speaker that is completely waterproof. It also has a pretty strong bungee cord on the back, allowing you to attach it to virtually anything. Since it is waterproof, you can toss it in the pool and continue to listen to your music. Additionally, it floats, so you can have the speaker floating in the pool playing music. Pretty sweet, right?
The reason why the UE Roll is so impressive is because of its size. It's a pretty small Bluetooth speaker but still puts out some amazing sound, as well as sporting some fantastic battery life. We're looking at around 10-12 hours. That's typically what you would see out of much larger Bluetooth speakers. The UE Roll typically sells for $99, however eBay has a refurbished model here for just $39.99. That's a pretty low price, and basically makes this a steal. At the time of writing this, it is available in Atmospheric Blue and Volcano Black.