If you don’t mind some low specs, and are focused on lowest price, a potato pi runs for about $30 IIRC, and is plenty to do small stuff like an openvpn server.

Gonna second the dell optiplex. Been using one for my home server for a while now, and it’s been perfect.

A refurbished Dell optiplex has been my move. Hasn’t failed me yet.

I ended up adding a healthcheck cronjob using healthchecks.io

Works flawlessly, and I’m sure it’ll help out in the future.