Seller accepts offers. Bid for 115 US$ was accepted automatically. That's the lowest I have seen recently. Others are sold at down to 150 US$.
Source >> 512 GB Intel Optane 512GB 288-poliger DDR4-2666 RDIMM persistenter Speicher NMA1XBD512GQS | eBay
Source >> 512 GB Intel Optane 512GB 288-poliger DDR4-2666 RDIMM persistenter Speicher NMA1XBD512GQS | eBay