hi, i was in your shoes not too long ago - i ended up buying a "no-name" mains cable off ebay - however, i did buy it from a well established ebay shop and it was obvious it was made of high-quality components. the cable itself did make a noticeable improvement to my system and i ended up getting a second lead for my cd player!
here is a link to the shop i speak off (i am not affaliated with them however i am extremely pleased with their products and customer service):
the leads i bought were very similar to the silver plated ones they are now selling for 40 GBP - these would make an ideal starting point IMHO.
of course if you want to get the best then 120 GBP will get you a SOLID SILVER (!!!!!!) mains lead.
best of luck!