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Get the Norton's from Lee Valley Tools -- no border involved, but you'll have some shipping costs:

Norton Water Stones - Lee Valley Tools

They have diamond plates and other goodies as well.
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I'd agree that your best bet is to find a finer-grit film or sandpaper. You can't buy abrasive-coated film at the local body shop, but it's available from woodworking supply stores.

My rule of...