Cheap computer bits

[ciphergoth]

Here's an easier one. Where do you go in London to buy things like cheap spindles of CD-Rs? In the wonderfully dodgy Silicon Group in Edinburgh, you can buy 100 CD-Rs for £18, with no packaging except a circle of plastic at either end and shrink wrap. I also need to buy a replacement keyboard, black ink for a HP DeskJet 690C, and a cable that plugs a sound card into a hi-fi.

Is there a particularly good shop on Tottenham Court Road that's worth checking first, or are the best bargains to be had away from TCR?