Yep just use what you've got! I'm running my server off a little workstation I got for free from work. I'm working on setting up another server for my sister on one of her old laptops then we'll use each other's as off-site backups and for redundancy. Work with your friends and family to get them off big tech too! Pretty much everyone has some old system sitting around that could be brought back to life and act as a server.