It's worth it. At some point you might enconter a service that requires SSL to work even on LAN. I treat them like pipes. The fewer pipes i need to pipe traffic through, the easier it is.
I use split DNS to access services locally, over the internet and via VPN. Everything is behind a Traefik proxy that uses wildcard certs. It enforces SSL for everything and I have just one pipe to think about.
If you can find DDR3 for free and your power is cheap/renewable, stick with it.
In any other scenario - upgrade to newer hardware. Don't buy e-waste.