Fine, let's say they mass-produce this supposed lens. What's the rent on the warehouse where they grow thousands of 8" fluorite lenses? What's the quality-control rejection rate on such a large lens? What's the amortized cost of the huge polishing machinery, given the amount of time the machine will need to polish such a large element to the proper specifications? How many other lenses could they turn out in the same amount of time if they're manufacturing more mainline lenses?
Enough from me, don't let me discourage you from contacting Canon and asking them to make this lens.