Not to excuse that mistake but FWIW there are third party manufacturers which sell prescription lenses for various headsets for as little as $50, so there will probably be cheaper options once they start making them for the Vision Pro. The cost to actually manufacture the lenses depends on the strength of the prescription, and most VR lens manufacturers reflect that in their pricing, but Apple appears to be charging everyone the worst-case price and pocketing the difference when you order a weaker prescription.
Also, you might be able to take your previous pair of glasses, remove the lenses and grind until they fit. I did something similar to make my own prescription sunglasses (glued in the lenses).
