1ct KAMRUI Mini PC Intel N5105 Windows 11 Pro 8GB RAM 256GB SSD WIFI6 4K Dual LAN (proxmox arbiter and also this will run your pfsense/opensense firewall vm/appliance)

2ct UM350 Mini PC 16 GB RAM 512 GB PCIe SSD AMD Ryzen 5 3550H Mini Computers (both of these will be the prox 2 and prox3 worker nodes)

Buffalo TS5410DN1604 TeraStation (NAS)

1ct Cisco Catalyst WS-C3650-24PS-S 24-Port Gigabit Ethernet Switch TESTED

All of that together with the Buy it now options are around $1000 USD total with shipping. That Buffalo NAS will need 3.5" drives. So add that to the cost.