Not to be discouraging but...
Schneider tried for years to release a *medium* format lens to compete with the "large" format Isco IIIL. They were unable to. Now this is the largest optics company in the world, with their specialty being high end photographic lenses and cinema lenses. They are building lenses for video, not NASA. If you ever saw a Cinemascope film, you watched it projected through a Schneider or an Isco lens. Schneider had their very small original Cinedigitar lens which was reported by their competitors to not have the same image quality as the larger lenses. But after years of saying they were working on one, none ever appeared; Only prototypes that they said were not suitable for public release. And they never were released.
So they bought Isco. Isco specializes in the large optics and is one of the only places that knows how to, or at least can, do it correctly. Isco is now the anamorphic division of Schneider, making all their large format A-lenses.
Now if Schneider worldwide couldn't do it (right), I'm not going to hold my breath many DIYers can do it right either.
To do it and produce a lens that does not cause ghosting, or has abysimal MTF, much less proper geometric expansion, vertical and horizontal focus, etc. etc. isn't as trivial as you made it sound.
Now, once you get into production, just to get your sample prototype piece made to see if your optical modeling was correct is big $$.
I'd love to see a cheap lens done well. Haven't yet. Becasue I know a lot about what it takes for the glass (we haven't even touched mechaincs yet), I won't hold my breath.
Then again, if you lower your standards and expectations enough on what a cheap lens does (or does not do) to your images, you might make a cheaper one. How much cheaper after all that R&D and pain, doubt enough to break even. You may be happier with a higher end prisim.
Or you found some secret the optical engineers at Schneider couldn't figure out.