A case for $5 is a good find unless you found literally the cheapest thing you could find. For a half decent case I'd expect $10-20, and more if you want something fancy.

What are you doing for storage?

I was weighing the same options recently and went with a n100 mini PC with 8gb RAM and 256GB m.2 SSD for $150. Absolutely no regrets.

I noticed you didn't list storage with your RPi5. Are you just using eMMC? I'd strongly recommend against eMMC as your only storage if you're doing anything write-intensive, since the life cycle of eMMC is generally much shorter than even cheap SSDs (and performance is much lower compared to m.2 via PCIe) and it's not something you can just swap out if it dies. On my existing Pis and other SBCs, I use any eMMC only for the bootloader and/or core OS image (if at all) and store anything else either on physically attached SD cards, SSDs, or mounted network volumes.

This additional storage adds even more cost to the Pi, even if you go with my recommended minimum of a SD card (low life cycle, but at least you can replace it). So now the 8GB Pi is $80 + $10-15 for case with fan and heatsinks + $10-15 for power supply + $15+ for a SD card or other storage = $115-125+ total.

In comparison, the $150 n100 mini PC comes with case, power supply, and storage. Both the included m.2 256GB SSD and 8GB RAM are easily replaced or upgraded using standard SSDs and laptop memory (up to 16GB DDR4-3200). The Intel n100 scores more than twice as high in Passmark compared to the ARM Cortex A76, and includes a full Alder Lake QuickSync engine (meaning it can hardware encode/decode a large variety of video codecs with the integrated GPU including very new and demanding ones like 10-bit AV1). I've stress tested it recently and it was capable of simultaneously transcoding 2x 4K HDR movies (both full UHD Blu-ray quality, one of them 60fps and 100Mbps bitrate) with tone mapping in Plex in real time while also doing a full library scan and credit detection. In addition, x86 architecture is still more broadly supported than arm, so compatibility is less an issue. (That said, in this particular case, the n100 is only fully supported in newer Linux kernels. I upgraded Ubuntu 22.04.4 to 6.5 kernel and installed a few other driver packages to get it fully working, which wasn't hard, but it's an additional step).

For me, in the end the price difference was at most $25 and the advantages made it clearly worth it.

That said, if all I wanted was a much lower powered SBC just to run a handful of light services, I might look at one of the cheaper Pis or similar and just accept that it'll eventually die when the eMMC dies (and back up any persistent data I'd want to retain).

What are you using for the NAS enclosure?

How does your music server work?