live green screen...cheap!

[CNYSkinFan]

So I know we have some decent video experts on this forum. I am looking for some help./ I would like to do a live green screen segment for an improv show I am working on. I am pretty sure I can construct a nice portable green screen for my use. What I would love to do is find a way to input video into a laptop, perhaps even through a web cam of a person against a green screen and impose pre-existing video footage on the green screen behind the person and send that video out live

I wm willing to do a small investment in equipment and really I am not to concerned about quality as it is for an improv show and not for professional consumption. So anyone got any ideas?

[Ibleedburgundy]

For the 100th time, it works better if you use a red light saber.