As everyone have said, it depends on what you want to have in your server. I started with an old lenovo I bought in mercado livre for 200 BRL. It was a DDR2 PC with 4Gb ram. I bought an ssd and installed Debian. Used for years. After that I tried to build a DDR3 PC. Made it with 800 BRL and it’s decent to run my docker containers like an arr stack, nextcloud, VPN, reverse proxy and vaultwarden.
As everyone have said, it depends on what you want to have in your server. I started with an old lenovo I bought in mercado livre for 200 BRL. It was a DDR2 PC with 4Gb ram. I bought an ssd and installed Debian. Used for years. After that I tried to build a DDR3 PC. Made it with 800 BRL and it’s decent to run my docker containers like an arr stack, nextcloud, VPN, reverse proxy and vaultwarden.