Like Dylan, I just ordered my first big white (300 2.8 LL) and the $6700 was a quantum threshold for me to cross. I don't know, perhaps after this getting past a 10K barrier will be easier, but somehow, I don't think so. I am wondering how other people do it? Are that many professionals (i.e., people making a decent living from photography using these lenses) to justify the price, and drive Canon profits, or are the lenses selling to people like me who are avid/rabid enthusiasts? Just a question.
The >$20,000 estimates seem really high to me. My understanding is that the front element is a significant cost driver for these lenses. Dropping from f/4 to f/5.6 is a big deal. Assessing the size of the front element using the focal length/max aperture, the 400/4 = 100 mm and 600/5.6 = 107 mm. And the patent is actually for 585 mm/5.6 = 104 mm. If this holds true, then I'd expect these 300-600 to be priced similarly to the 200-400. Say ~$12,500?