They estimated $200k for a single NVIDIA GPU-based CPU complete with RAM and networking. That's where my number came from. (RAM and especially very-high-speed networking is very expensive at these scales.)
"Add it all up, and the average selling price of an Nvidia GPU accelerated system, no matter where it came from, was just under $180,000, the average server SXM-style, NVLink-capable GPU sold for just over $19,000 (assuming the GPUs represented around 85 percent of the cost of the machine)"
That implies they assumed an 8-GPU system. (8 × $19,000 = $152,000 ≈ 85% × $180,000)