Because that's a different price point, that's getting near 100K, and the availability is very limited. I don't think they're even selling it openly, just to a bunch of partners...

The MSI workstation is the one that is showing some pricing around. Seems like some distributors are quoting USD96K, and have a wait time of 4 to 6 weeks [0]. Other say 90K and also out of stock [1]

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  0: https://www.cdw.com/product/msi-nvidia-gb300-wkstn-72c-grace-cpu/9087313?pfm=srh
  1: https://www.centralcomputer.com/msi-ct60-s8060-nvidia-dgx-station-cpu-memory-up-to-496gb-lpddr5x-nvidia-blackwell-ultra-gpu-1x-10-gbe-2x-400-gbe.html