Supermicro X13SWA-TF Motherboard (16 DIMM slots with Xeon W-3500)= ~$1,000
E-ATX case = ~$300
Power Supply= ~$300
Xeon W-3500 (8 channel memory) = $1339 - $5889
Memory = $300-$500 per 64GB DDR5 RDIMM
Memory will be the major cost. The rest will be around $5,000. A lot less than "$100,000"!