[necovek]

In terms of production, SSD flash chips that go into SATA and NVMe drives can be pretty much the same: only the external interface can be different.

The biggest cost driver for flash chips is not the speed they can be read from and written to in bursts, but how resilient they are (how many times can they be written over) and sustained speed (both based on the tech in use, TLC, SLC, MLC, 3D NAND, wear levelling logic...): even for SATA speeds, you need the very best for sustained throughput.

Still, SATA SSDs make sense since they can use the full SATA bandwidth and have low latency compared to HDDs.

So the (lack of) price difference is not really surprising.