There are dozens of videos on YouTube showing how to build your own Bluetooth speakers or boom boxes. A number of them have ready-made Bluetooth radios and audio amps in common. These Bluetooth and audio amp modules are interesting because they are quite cheap (most under $20–see this one on Amazon as an example), fully built and tested, and easy to interface to. You could probably build one of these without even knowing how to solder! It’s a simple matter to fit one of these small BT/amp boards into a box with speakers you’d mount yourself, or even retrofitted into an old plastic-fantastic boom box you have laying around, or maybe purchase for next-to-nothing at a Goodwill store. All you really need is the housing and the pair of speakers. Everything else can go!
For those of you that are old enough, remember the little transmitters you could buy or build that output a fairly unstable signal somewhere on the 88 to 108 MHz FM broadcast band? They were often called FM or wireless mikes. Plug one in, and tune in to it on of your FM radios you happened to have around the house. They worked sort-of OK, but were never very good, and the 9V battery usually went dead in a few hours’ use. In the Bay Area, you also had lots of trouble finding a fairly open radio channel to use. The whole system was, as the British say, kind of fiddly. It was more of a science experiment than anything else..
With Bluetooth, it’s so much easier, and the sound is just light-years ahead of the old analog FM stuff! Most of us carry smart phones with Bluetooth built into them already, so it’s almost trivial to play the music or podcasts on your phone through your car stereo system or an inexpensive set of Bluetooth tabletop speakers. Most of the cheaper BT speakers don’t have such great sound, though. They tend to be small and tinny-sounding, but that’s not Bluetooth’s fault.
Anyway, here are several links to folks that have built their own Bluetooth speaker systems. Maybe they’ll inspire you to roll your own:
Here’s an under-$20 BT dongle that plugs in to any 3.5 mm jack, giving you instant Bluetooth audio for a home stereo system or maybe even a car stereo. This is sold by Parts Express (good company–lots of speakers and speaker kits as well), but there are many similar and cheaper units on Amazon as well: