This is a good price for a dual PCI-e SSD expansion card.
Apparently these work in PC's as well.
They regularly sell anywhere from $150 - $250
Model: M.2 PCIe NVMeCapacity: 2 x SSDConfiguration: QM2-2P-344Verified Purchase
Pros
• PC compatible - Not only for QNAP systems
• PLX bridge chip - Does not require a motherboard w/PCIe bifurcation
• Bootable
• No special driver required - Windows detects and auto installs drivers
• Heatsink + fan included
https://www.ebay.com.au/itm/184035445235
Same price here too. Looks like you can get $5 off by purchasing through the eBay mobile app with code PRONTO5.