Outsourcing Admin on the Weekend

I would like some advice about a service I am thinking about starting. I work as a full time network administrator. What I want to do is get other network admins like myself that would like some side-jobs on the weekend. Through my web site, small businesses would be able to hire an admin to come in on the weekend while the network isn’t being used as much and do specific jobs. This way the company wouldn’t have to hire a full-time network admin. What should I charge for this type of service? Does this sound like a good idea? I am located in the bay area (California).