In looking at replacement for fully-wired speakers in classrooms, I ws finally able to find some speakers that are under $200, wireless and have good sound quality. These speakers are from Cables Unlimited / Audio Unlimited and seem to be a great little solution. The speakers can use batteries or be plugged-in and wall-mounting is simple (no extra brackets, etc.). There are screw holes on the back of the speakers to rest on the wall. Range is good, quality is fine for a classroom to watch a DVD, listen to language lessons and other activities.
In my tests, the speakers have performed great. I would not say these are top of the line audio for audiophiles, but if the goal is to remove cables and have decent quality, these are fine and much better than tethering a teacher to a specific area of the room to hook up their laptop. The other nice aspect is you can add more speakers to the mix. They sell additional speakers w/o senders for just this purpose.
The ONLY drawback is they only provide 2 channels for communication. Which means, if you had systems in rooms next to each other, you really have to watch which channels you are using so you will not have speakers jumping to the wrong source. This could be an issue when you have multiple classrooms side-by-side. I do wish they would allow more than just the 2 channels, but for $150 is a great deal and they operate as expected with great range.