For wireless APs, Ubiquiti equipment is fairly well-priced and capable for prosumer gear, although I’m beginning to be less enthralled with the controller model for APs. They also can operate on 48vdc passive power, or 802.3af/at PoE, which might work nicely if you have a compatible switch.
I’ve heard from colleagues running Plex on Proxmox that core count is nice, except when doing transcoding, where you either want high single-corr performance or a GPU to offload. So an AMD Epic CPU might serve you well, if you can find one of the cheap ones being sold off from all the Chinese data centers on eBay.
Now with that said, have you considered deploying against existing equipment, and then identify deficiencies that new hardware would fix? That would certainly be the fastest way to get set up, and it lets you experiment for cheap, while waiting for any deals that might pop up.