https://www.newegg.com/g-skill-64gb-288-pin-ddr4-sdram/p/N82...

Here's a 2TB SSD for $143:

https://www.newegg.com/leven-2tb/p/1B0-016A-00002?Item=9SIAW...

But then you don't have PCIe 4.0 and it's 4x16GB instead of 2x32GB and it's SATA instead of NVMe.

Here's how you spend >$700 on 64GB of memory:

https://www.newegg.com/ballistix-64gb-288-pin-ddr4-sdram/p/N...

$894!

But wait, here's the same thing for $310:

https://www.newegg.com/ballistix-64gb-288-pin-ddr4-sdram/p/N...

It's a different color. Apparently that's what you get for the extra $584.

There's getting cheaper stuff and then there's just paying a different amount of money.

The $143 SSD you found is 540Mb/s. So < 1/10th the speed.

Both the Samsung and the Apple SSDs are just a bad fit for a machine like this. For a non-I/O bound workload it's paying money for nothing. For a read-bound workload, the machine has 64GB of RAM, so you'd need a working set larger than that to have to care, and that's pretty rare. For a write-bound workload, at those speeds, you're going to melt a consumer-grade SSD and need an enterprise one. So you don't want the faster one in this machine; either it's not worth the price or it won't survive that amount of write load.