In terms of design, I'm going a different route: Instead of a bunch of smaller LEDs, I'm doing 12x larger LEDs (6x 2700K, 6x 6500K). I'm using the Bridgelux V18 Thrives, so the CRI should be quite good (95+), as should the overall efficiency because I'm running them at pretty low amps relative to the spec sheet.
I use a 200w vivosun pointed at the wall during the short daylight months.
Costs a fraction of what you mentioned at roughly $150. Or $300 if you really want to go as high as 400w.
Makes the whole room feel like you've got bright sunlight pouring in.
My wife made fun of me at first, but now also has one for her office.
I did see the Brighter and Rhythm lamps before but their way out of my price league.
In Edinburgh (Scotland at 56 deg N) during December, it's sunrise at 08:30 and sunset at 15:30. And there's plenty of folks at higher latitudes that may be interested as well.
My current "design" is basically just strapping all the pieces together, so it'll leave a lot to be desired in terms of aesthetics for folks who want it to be more nicely integrated into their living environment.