For Samsung PM830 msata 256GB SSD 256G Mini pci e Solid State Drive MZ MPC256D Read 470MB/s Write: 310MB/s|ssd solid state drive|ssd netbookssd - AliExpress
NEW hard disk Solid State Drive For SSD PM871 mSATA 128GB MZ MLN128D FW EMT42D0Q 1.8" R/W Tested SATA 6Gb/s|Laptop Motherboard| - AliExpress
1TB SSDNow M.2 2280 SATA 6GB Compatible with HP/Compaq 15 Series Notebook 15-da1xxx (Intel Core processors) by CMS d68 - Computer Memory Solutions
You can get the 512GB SSD the Steam Deck uses for $82.50 from DigiKey. : r/pcmasterrace