From Amazon, og as far as can tell.

Get yourself the cheapest n150 box you can, the 4 port versions are good im case you decise to upgade and convert it to a fw later. Get a 4tb 2.5 ssd if you afford it and a chewp dual or more jbod external for safe backups.

Every year upgrade and stick to proxmox and opnsnese untill/unless you have reason otherwise.