$40 off over at Newegg right now. For $90 you can snag yourself this PCIe 3.0 drive, which may not be the fastest around today, but should make for a great drive to load your game library onto.
During Black Friday, we found this drive going for $79, so you're not getting it for the absolute cheapest it's been. However, this is still a decent price for 1TB of storage, and cheaper than Amazon has it, at $103.
WD SN550 NVMe SSD | 1TB | PCIe 3.0 | $129.99 $89.99 at Newegg (save $40)
The SN550 delivers plenty of storage for less cash than you might expect. It’s not the top performing NVMe SSD ever, but at up to 2,600MB/s sequential read and 1,800MB/s sequential write, it delivers all the speed your Steam library could ask for.
If you're not using a PCIe 4.0 or PCIe 5.0 platform, you're not going to benefit much from using one of the best NVMe SSDs going today in your machine. You will max out the available bandwidth, but you'll be leaving a lot of performance on the table.
Similarly, for a game library drive, you might not notice a tremendous difference in performance between a PCIe 3.0 drive and a PCIe 4.0 drive, as there's only a small difference in loading times between speedy NVMe drives of any kind. Perhaps once DirectStorage arrives we'll have more reason to upgrade our library storage, but for now you can buy a cheaper drive and keep that cash for other, more meaningful upgrades.