Waffle iron with changeable plates for butter galettes
You should be able to use the waffle iron as is and just not close it, I would think.  Though I am also not able to find a replacement, except through alibaba.

Edit based on apparent flag and mod comment:

All a special galette plate will provide is the shape.  You can still make the batter, spoon a couple of tablespoons onto a hot waffle iron and yield exactly the same thing, albeit in a different shape.