It's pretty hard to achieve a high quality audio with a sub at the price point, but the Klipsch Promedia 2.1 should fit that bill. I would say the Swans M10, but they lack bass for movies. The Promedia has a much larger sub though.
Another thing you could do would be refurbished M-Audio AV40s and a separate sub, but then that would run over your limiti.
Another thing you could do would be refurbished M-Audio AV40s and a separate sub, but then that would run over your limiti.