Do you guys think this is a good buy? Japanese Waterstone Ceramic Flattening Stone Sharpening - eBay (item 150371095003 end time Oct-06-09 08:43:13 PDT)

It's 150 grit so I don't know exactly if it would be good on my higher grit
stones (which are all Norton... + "C12k"). I'm getting tired of buying sandpaper and getting out my huge piece of glass to lap my stones.