Mostly teasing but my guess would be $500k+ since they'll likely price it so that it is the same $ as the equivalent NVIDIA cluster (or very close to it).
A single Nvidia H100 costs somewhere around $30,000 each, so a GPU server with every slot populated costs about $300,000.
https://www.servethehome.com/graphcore-celebrates-a-stunning...
Not sure about the H100, but it seems to be more supply constrained (hence pricier) atm.
Now, the real question is how many HGX nodes "equals" a single CS2 node. The math here is extremely fuzzy, as the benefit to such extreme node consolidation depends on the workload, and the CS-2 takes up less space, but the HGX cluster will have more directly accessible RAM and better turnkey support for stuff since its Nvidia.
This is getting so real so fast.