Really just the GPUs. PSUs aren’t that expensive maybe 100-200 for a good 750W-1000W one

Kind of feels like if you spend $40K on your GPU setup, you don't want to cheap out on the PSU.

Still, you're right, I have a 1200W PSU for a single RTX Pro 6000, cost ~500 something, so still the PSU shouldn't be that large part of the total budget.