Tronsmart has announced the Studio 30W SoundPulse as its latest wireless speaker. It is rated to cover an open space of up to 10 meters in size with 2.1 channel sound for up to 15 hours per charge. Unlike most portable accessories of this type, it has a housing made of aluminum, yet is still IPX4-rated. It goes for ~US$70, or less with a coupon active at the time of writing.
https://www.notebookcheck.net/The-latest-Tronsmart-Studio-portable-speaker-has-a-metal-chassis-and-a-5-000mAh-battery.556241.0.html