Amazon has Anker portable speakers on sale for under $30
Anker Premium Stereo Bluetooth Speaker Review
Anker Soundcore Motion Boom speaker review: Bluetooth for the beach | TechHive
Amazon.co.jp: Anker Soundcore Motion X600 Bluetooth Speaker, Spatial Audio, High Resolution Sound Playback, 50W Output, IPX7 Waterproof Standard, Up to 12 Hours Playback, Pro Equalizer Function, AUX Compatible, Space Gray : Electronics
Speakers | Wireless Bluetooth Speakers - soundcore US
Amazon.co.jp: Anker Soundcore Motion+ Bluetooth Speaker, Waterproof, Deep Bass, apt-X, 30W Output, 12 Hours Continuous Playback, IPX7, Passive Radiator, Compatible with iPhone & Android, Black : Electronics