We own a 36” subzero refrigerator with freezer on bottom. It is two years old.
We have approx the same model as she has, but we opted for a custom front instead of stainless steel. The price of ours was $7,815.
If I recall the stainless steel grill, and front and handle, would probably add about $1,000. So round up to $9,000.
She has two of these units. $24,000 is probably a bit high. But they are expensive and she probably has no idea.
As an aside - they are great refrigerators!
In the coming Great Depression II, I'll buy me one.