An old laptop with a cracked screen turned into a file server and media backup box using nothing but a lightweight Linux install and an external drive I already had. No new hardware purchase needed, just about two hours setting up SSH access and a scheduled backup script.
The screen being broken was actually fine, everything runs headless over SSH from another machine on the network. Closing the lid with an external monitor unplugged keeps it running instead of sleeping, which took some digging in the power settings to figure out.
It’s not fast, but for backing up photos and running a small file share for the household, an eight-year-old laptop handles it without breaking a sweat.