Are there more products similar to this one in function for a significantly lower price that you'd recommend? Like even just with 3-4x Gen 5 spots instead of 8.
ASUS Hyper M.2 PCIe x16 Gen 5 NVMe Card with 4x M.2 Slots.
It's cheap because it simply provides 4x4 PCIe lanes, and cooling on a single smallish single slot card. They also do (cheaper) PCIe 4 ones as well, and I have a PCIe 3 version of the card which you might be able to find for even cheaper, and depending on need.
You will need to make sure that the PCIe slot that you intend to use is correctly setup in the BIOS if it is not automatic, check with ASUS for the newer versions but the PCIe 3 version needs the BIOS to be set to 4x4x4x4 (or similar), then the OS simply sees all devices installed exactly as though they had been plugged directly into the motherboards very own M2 slots, any number of M2 drives can be used from 1-4, in any mix of capacity, make, model, and PCIe version and then everything is handled by the OS.
There are other products out there, I know that ASrock have one, and MSI has one that supports at least 2 M2 drives, and FYI, they (should) all be drop in compatible with any board, my g3 ASUS Hyper card worked just fine in an ASrock board. No doubt there are other brands out there, but I only have experience with the ASUS Hyper g3 version. Good Luck.