Has anyone ever thought of contacting JML Optics? They've made good lenses themselves so seems like a quality place to try
I believe I read somewhere on their site their founder was an old Ilex guy

They have a coatings section and it appears to say MgF2 coating for a smaller diameter lens would be in the $25 per surface range
but I could be misreading that totally


You can see their setup and process on a lens making Youtube video