You can get x variants for under 100 too but you got to be more patient. Larger resellers don’t always understand the difference in models. You don’t have to go this in depth but look at the rear view for addons on the eBay listing. I usually don’t worry about buying ones with warranty/etc and I’ve only been burned once (probably water damage).

In my experience, if you’re wanting to use a USB Ethernet 2.5g or more, you may want to come up with at least a USB c port. I get that it should work with USB 3 but the speeds in practice just never worked out for me. I could have been facing those reliability issues you mentioned. Experiments in that area may eventually lead you back to scavenging for models that accommodate a riser card for 10g which is a very well weathered path. If you want Ceph, it’s not absolutely required but you’re probably going to end up there. I wouldn’t do Ceph again.

Somewhat similar on the CPU, I only discovered problems when I started experimenting with mass video re-encoding which is probably similar to the workload on Frigate. With the top on, I can only really use about half the cpus consistently. CPU upgrades are also mostly out.

Minor segue: If you haven’t checked out the servethehome forums, highly recommended. It’s probably the best source of knowledge on these.