DW sells the same cases for less than Phong does, but your biggest hit, by far, comes from the Valjoux 72 movement (once you are actually able to acquire one) & all the ancillary gen parts you need. Figure $1,500+ for those (plus the cost of the case) and you still have to get everything constructed into a cohesive watch. Considering the amount of work required, I can see why Phong charges what he does for a fully-assembled Daytona.
I proposed the idea to DW that he consider selling the 7751-version here (the 7751 is the manual-wind version of the 7750), but he felt there would not be a sufficient number of paying customers (retail would run around $800) to make it worth his while. And my informal poll, while showing there is some interest here, did not convince him otherwise. But, I agree with you that such a watch is sadly missing from the marketplace.