Search:

the King 1k/6k is a good value stone. It's a little soft, so you may need to lap it more often than a more expensive stone (easily done), but it's still fine enough to give a really good edge.

If...

I'd be wary of buying cheap, no-name, man-made stones. I've found that some of the compressed ceramic stones give off way too much slurry, in fact, they virtually disintegrate whilst you are using...