You can build a useful lab pretty cheaply with older enterprise equipment. Examples:
The point is not to own the newest hardware. It is to have enough real equipment in front of you to build something, break it, and figure out why it broke.
- Cisco ISR 2901 / 2911 routers — often inexpensive and good for routing, NAT, ACLs, VPN concepts, and IOS practice.
- Cisco Catalyst 2960 / 2960X switches — great for VLANs, trunks, STP, port security, and general switching.
- Cisco Catalyst 3560 / 3750 switches — useful if you want Layer 3 switching and inter-VLAN routing.
- Cisco ISR 4321 / 4331 — newer IOS XE platforms that are still affordable used.
- Dell PowerEdge R610 / R620 / T320 / T420 — cheap server hardware for virtualization, Windows Server, Linux, storage, and domain labs.
- HP ProLiant DL360 / DL380 G7-G9 — another common source of inexpensive enterprise server hardware.
- Small business firewalls like older FortiGate, Sophos, or Cisco ASA units — useful for firewall concepts if licensing is not a blocker.
- Used enterprise access points from Cisco, Aruba, or Ruckus — useful for learning wireless management and enterprise Wi-Fi.
The point is not to own the newest hardware. It is to have enough real equipment in front of you to build something, break it, and figure out why it broke.