Yeah, I think the net cost of the part would be low, but...
Taking somebody's slide out of box, putting it onto a machine, making sure it is all located correctly, running it, cleaning it off, coating it, and putting it back into a box, compared to writing a program for a multi-axis turning center that feeds a bar and turns it into a slide without it being touched by a human hand. It is probably start to finish faster, cheaper (including overhead), and less error prone.
And if you do make an error, you need another stick of metal instead of explaining to some dude that his precious slide is ruined. When I worked for my wife's print shop we would have people bring in stuff like their poster from a concert in the seventies from the time they got back stage and got autographs from the band and smoked weed with them, and they would want us to laminate and mount it. If we botched up a print that we had printed we would say shit and print another one. Typically the employee that screwed it up would quietly ask their colleague for a reprint and we wouldn't even know. Not so easy with the concert poster...
I have been checking them out also. At this point I have no current need, but am always planning the next step.