AO.com have the Samsung HW-K550 (340W) on offer for £299 at the moment, they have also got an offer of £130 off when buying selected TV's. I have just tried and found that you can order and use the code without buying a TV! So it works out at £169 with free delivery.
Code is MEGABOOM130
Silver here too:http://ao.com/product/hwk551-samsung-soundbar-silver-41268-111.aspx
Most stores seem to have this for £250-£300 so seems like a decent price
The HW-K550/1 Soundbar is perfect for adding that extra audio punch to your movies, games and TV programmes. Designed for positioning in front of the television screen or even securing to a wall, the soundbar delivers surround sound expansion, wirelessly.
Wireless TV Connection
The HW-K550/1 is the wireless way to upgrade your TV sound. Connect your soundbar to your television without wires and enjoy superb, powerful sound that brings programmes, movies and music to life. TV has never sounded so good.
This sound bar's six built-in speakers deliver a thunderous 340W of audio power. This way, you'll get the punch and warmth needed to lose yourself in your movies and TV shows. Fill your room with every explosion, harmonic soundtrack boom and drama twang with this top-notch sound system.
Clear vocal performance
Experience a clearer vocal performance when watching your favourite movies and TV shows. Clear Voice Technology is designed to lift the spoken word - conversation and speech - from background noise. The result is a win for the most immersive experience as you won't have to strain to hear movies with a lot of dialogue.
With an active wireless sub you don’t need to worry about wiring and you can position the unit anywhere in the room which suits. Out of sight but still a key part of your audio setup, you can delight in the power of deep bass from a subwoofer which brings with it an immersive experience.
Wireless music connection
Your HW-K550/1 SoundBar can be easily used to enjoy your favourite playlists too. Simply connect your Bluetooth enabled phone or tablet to your soundbar and start streaming music stored on your phone or music services such as Spotify or Deezer.