It comes w/ the serial number engraving. If you want like the big 'C' on the bottom of the switch button, which many do, that's extra.
I see. I was confused because many of the orders, mine included, have, on the far right "names and images" column, the #512 etc.. Is that an additional # engraving that costs money?
Here is example:


I recently switched SN with vaporooski (who is AWESOME, btw, ty vaporooski) and during the switch the #512 was added under the names and images section. If the SN 512 is already going to be on the mod, I don't think I need to pay additional monies for additional SN engraving...