Since Sony's PlayStation 5 Beta Firmware release to testers that adds support for PS5 M.2 SSD Drives, the PS5 Beta System Software FAQ and confirmation of FireCuda 530 NVMe M.2 PCIe Gen 4 / WD_BLACK SN850 SSDs with heatsinks working on PlayStation 5 those in the PS5Scene will be happy to know Micron Technology's Crucial P5 Plus NVMe and even ADATA's slower XPG Gammix S50 Lite NVMe Solid State Drives have been tested as compatible with PS5 also. 
Pricing and Read/Write speeds for the Crucial P5 Plus NVMe SSD are 500GB for $107.99, 1TB for $179.99 and 2TB for $367.99 (minus the recommended aftermarket heatsink) with up to 6,600MB/s Read speeds and up to 5,000MB/s Write speeds.
In comparison, the pricing and Read/Write speeds for the slower ADATA XPG Gammix S50 Lite NVMe are 1TB for $129.99 and 2TB for $269.99 (minus the recommended aftermarket heatsink) with up to 3,900MB/s Read speeds and up to 3,200MB/s Write speeds alongside a screenshot below from Sean Hollister:
The ADATA XPG Gammix S70 NVMe is also available in 1TB for $169.99 and 2TB for $309.99 (minus the recommended aftermarket heatsink) with up to 7,400MB/s Read speeds and up to 6,600MB/s Write speeds.
FFVII Remake Intergrade (PS5 version) load time with SSD
So it appears at least some low-end and under-spec SSDs work with PS5 despite being below Sony's recommendation for speeds of at least 5,500MB/s... however, they may not be future-proof as technical director Mike Fitzgerald of Insomniac Games notes:
The Gen4 drives we tried that met the recommended specs gave results almost indistinguishable from the internal SSD. The rest of the I/O path still in use (hardware Kraken decompression, etc.) is definitely pulling its weight in delivering the crazy loading moments in Rift Apart.
We tried some below-spec Gen4 M.2 drives as well and saw up to 15% slower loading in the most SSD-stressing areas of the game. Not too shabby, but keep a close eye on technical specs if you’re making an SSD purchase, as our game does rely on high-quality storage.
In conclusion, to quote from TheVerge.com on whether to consider getting slower but less expensive PCIe Gen4 Solid State Drives for PS5:
"I'm not so sure, because Sony picked its recommended SSD spec for a reason — even if today’s games and today's PS5 aren't taking full advantage, developers may need that additional headroom in the future.
They've been promised 5,500MB/s to deliver instant game worlds, and I'd hate to find out I bought the wrong drive years down the road."
Pricing and Read/Write speeds for the Crucial P5 Plus NVMe SSD are 500GB for $107.99, 1TB for $179.99 and 2TB for $367.99 (minus the recommended aftermarket heatsink) with up to 6,600MB/s Read speeds and up to 5,000MB/s Write speeds.
In comparison, the pricing and Read/Write speeds for the slower ADATA XPG Gammix S50 Lite NVMe are 1TB for $129.99 and 2TB for $269.99 (minus the recommended aftermarket heatsink) with up to 3,900MB/s Read speeds and up to 3,200MB/s Write speeds alongside a screenshot below from Sean Hollister:
The ADATA XPG Gammix S70 NVMe is also available in 1TB for $169.99 and 2TB for $309.99 (minus the recommended aftermarket heatsink) with up to 7,400MB/s Read speeds and up to 6,600MB/s Write speeds.
FFVII Remake Intergrade (PS5 version) load time with SSD
So it appears at least some low-end and under-spec SSDs work with PS5 despite being below Sony's recommendation for speeds of at least 5,500MB/s... however, they may not be future-proof as technical director Mike Fitzgerald of Insomniac Games notes:The Gen4 drives we tried that met the recommended specs gave results almost indistinguishable from the internal SSD. The rest of the I/O path still in use (hardware Kraken decompression, etc.) is definitely pulling its weight in delivering the crazy loading moments in Rift Apart.
We tried some below-spec Gen4 M.2 drives as well and saw up to 15% slower loading in the most SSD-stressing areas of the game. Not too shabby, but keep a close eye on technical specs if you’re making an SSD purchase, as our game does rely on high-quality storage.
In conclusion, to quote from TheVerge.com on whether to consider getting slower but less expensive PCIe Gen4 Solid State Drives for PS5:"I'm not so sure, because Sony picked its recommended SSD spec for a reason — even if today’s games and today's PS5 aren't taking full advantage, developers may need that additional headroom in the future.
They've been promised 5,500MB/s to deliver instant game worlds, and I'd hate to find out I bought the wrong drive years down the road."
