I was thinking around $25 or so, plus the shipping. As to how much Cerrosafe, I'm not sure exactly, would have to be enough to fill the bore through the area to be ported. The Cerrosafe can be remelted and reused from what I understand, so you should be able to do multiple guns with the same batch. Brownells sells it by the pound and 1/2 pound. I would probably just get a pound of the stuff.
The manufacturer shows the jig on 10-28ga barrels in their drawings, but doesn't specifically say what sizes it will work on. I'm assuming 10-28ga though.
Jeff, when I talked to Brownells gun tech, I was specifically asking about the rifled barrels, as the manufacturer of the jig recommends honing the barrel of a smoothbore to remove burrs. They informed me that several people have reported good results with the Cerrosafe.