Leonard Grind-R-Lap

[Jerry Lawrence]

I recently acquired a Leonard Grind-R-Lap grinder, with no sharpening stone. I found one online here:http://accu-finish.com/product/5-inch-diamond-wheels for $169, but haven't found any others. Wondered if anyone knew of these wheels available for any less than that. Also, which grit would be best for keeping a sharp edge on standard carbide tipped metal lathe tools, used for cutting wood and soft stone.
Thanks for your help!