As I said to the previous poster, you are more likely to evoke useful responses at the Home Theater website (http://www.hometheater.com/) than you will here.  If you are willing to give up on the wireless requirement, good quality solutions are possible in your price range but wireless is a problem as it means, of necessity, higher cost, poorer quality or both.

En passant, if you can accommodate it, it is generally better to get a 5th matching speaker for use in the center rather than an inexpensive, dedicated center speaker.

You could also ask at www.hometheatershack.com they have a very lively and active forum. I'm certain you will get plenty of responses from the posters there.