I just purchased some 3M Micron Finishing Paper from Progress Tool. They carry a large selection. These aren't micro-abrasives but they are advertised as the grits we'd use to sharpen. I purchased 2 sheets of each and they cost me $13.80 shipped. I'll let you know if they're good after I get them.
Progress Tool carries many different papers. However, these are definitely not appropriate for using with razors. These papers feel more like a cloth than sandpaper. Don't waste your money.. like I did.