when it was new in 2012 is was 20k it's hard to find an actual solid number price but because it was only sold for custom orders
https://hardforum.com/threads/extremely-rare-intel-slc32-xeon-x5698-4-40ghz-dual-core-12mb-l3-lga1366-cpu.1981529/
Just been looking around at the Intel xeon 58 chips and I saw this chip pop up and people were talking about it costing $20,000 in 2013 seems a bit ridiculous for a dual core CPU