Sure, but I only really know of http://www.dell.co.uk/ and http://www.toshiba.co.uk/. http://www.pcworld.co.uk/gbuk/index.html, http://www.currys.co.uk/gbuk/index.html and http://www.tesco.com/ are some retailers but I have no idea if they're overpriced or not.
Oh, and £300 is $474.