I want to build a small rackmount NAS for backups. My main requirements are fairly cheap (like $100-$150) and ability to connect 2 SATA disks. I plan to run Debian, and the software I use is pre-packaged for x86, armhf and arm64. When it comes to the SATA disks, I'd prefer 2 onboard ports (not using onboard USB adapters), but am happy to buy a (mini)PCIe adapter to use, or a port multiplier (that'll still be faster than my current setup). I will be building it all into a gutted case from an old switch or similar, so I don't need a case. Any suggested boards?