McMaster Carr in Chicago, IL sells greaseless.

McMaster-Carr

It is not listed as "Greaseless Buffing Compound" but rather as "Satin-Finish Buffing Compound". When you actually get it, the tube does say Greaseless Buffing Compound. It is made by a company called Kocour and the tubes weigh about 2.75 lbs. each. One drawback is that McMaster does not have a 600 grit. That you'll have to get elsewhere.

Best,

Mark