Launch year
The oldest gear here, from the Catalyst 2960 of 2005 and HP's ProCurve 2610 and 2810 to the ISR 2921 and SRX240 of 2009. Every one with a published date is past the maker's end of support, from the 2960-24TT-L in 2019 to the ASA 5505 and ISR 2921 in 2022, so expect no new software or security fixes. They still teach the same commands, which is why CCNA students keep buying them. Keep them on a lab network rather than facing the internet, and check the software version in the photos.
6 models we cover.

Cisco
Switch$50–$100 typical ask
96 on eBay
Cisco
Firewall$25–$55 typical ask
196 on eBay
Cisco
Router$80–$170 typical ask
132 on eBay
Juniper
Firewall$230–$1,150 typical ask
12 on eBay
Aruba and HP
Switch$35–$90 typical ask
36 on eBay
Aruba and HP
Switch$45–$210 typical ask
57 on eBay