There's no question about it. The cheapest 4TB SSD you can get right now is the Acer FA200 4TB internal SSD is now $480 at Amazon, which I previously saw listed for $530. In the UK, the FA200 is priced at £430 for anyone who needs extra PC storage.
That makes it the cheapest SSD per TB since February this year, at less than $0.12 per GB. Of course, thanks to the component crisis, that's still a lot more expensive than it was a year ago - but unless you're willing to help me install a Flux Capacitor into my car, it's the best price for an SSD of this capacity and speed that I've seen.
Update October 8. I've checked the price and Acer's SSD is still $480 post-Prime Day. My other picks below are all significantly more expensive and costs have increased.
Why I recommend this deal
At this price, that works out at $120 per TB (or a little under 12cents per GB, if you prefer), which is the most affordable I've seen in the deals.
The drive is well-specced for both general computing, as well as heavy workloads like video editing, 3D rendering, and gaming. Connectivity-wise, it features a PCIe Gen4 with hitting read speeds of 7,200 MB/s and write speeds of 6,200 MB/s.
It compares very well to competing 4TB PCIe 4.0 SSDs like the Samsung SSD 990 Pro ($938.99), which costs almost twice the price for a marginally faster performance or the Western Digital 4TB SN5000 Blue, which costs the same but has a way slower performance.
The FA200 got a solid 60% from our sister publication, Tomshardware. The reviewer noted that it has an above average overall performance, is power efficient and runs cool but suffers from poor sustained write performance.
