You find no ready off the shelf solutions that cost less than a few thousand. The fact you noted an old PC tells me you want to install something there.

I can not offer support for this here but will note that I've seen IT staffers use Linux and all the tools there. They usually spend a month to set it up. We don't allow that sort of work in our office since it turns out to be a support tar pit and black hole combined. I won't go near it because of the same reasons.

Now you know and you have choices to make.

-> If you want something easier, go look at NetLimiter.