I use mine for TTS SmartThings announcements (e.g. “The side gate is open and there is motion by the utility room door.”) Using custom DTH/smartapps available here. Can also be used for music of course.
DTH: RELEASE Generic Media Renderer (DLNA Speakers). Cheap Sonos Alternative (Update V2)
I just got one for $38, but at $29 that is a good deal. One warning - they need to be connected via USB full time for power - the battery life is pathetic.