It is a terrible idea, what if there's thunderstorm and your power goes out?
What if you get digged?
What if you get hacked because you don't know how to configure your server for security?
What if your harddrive fails (most, if not all hosts have raid setups and take their own backups, and some even have redundent servers so if one fails your site keeps going).
What if your server gets lots of traffic and your ISP flags you (you'll likely lose your internet altogether).
I could go on and on. It's not worth it for a couple buck a month for a proper host.
And spidahost will work with you, I've had a few off the wall requests that they were willing to let me do. (SSH for instance).
The greatest multiplayer text adventure ever...