Networking wireless cameras

Hi, I could use some advice on a project. I have a metal building in my back yard with linksys wireless cameras. I only have one camera in place now for testing but will have 4 total. I have a linksys wireless-G router attached to my computer in my house. I can't get a signal from the camera to the router through the metal building. I will need a switch or router to connect all the cameras. Is there a way to get this signal outside the building so it will work or would I be better off cost wise to just run cable? Thanks for any advice.