I'm so close to pulling the trigger on trying some of these lower grit inexpensive Japanese Natural stones. There's a 1000 grit about halfway down for about $33 that could be ripped in half. CLICK HERE and go to the Woodworking tab and then pick the stone option. There is a Bester brand 1K grit ceramic stone for $40 that is solid. I've never used the brand, but another potential option to rip it lengthwise.
Chris L