For things to be cheaper you don't have to use a isight camera. I have a cheapy Philips laptop webcam that I stripped down. I used this in my Dell mini 9 laptop. My laptop had enough room to fit a small Belkin 4 port USB hub. I had to desolder the USB connectors and hardwire everything. For the wiring to the webcam I used some packaging tape and some gold foil from a hobby shop, I created a 4 pin cable out of it and ran it from the USB hub to the webcam's circuit board. This gave clearance for the display hinge.

Right now i'm currently trying to find a spot to add a USB port because with the HUB that will only let me use 4 USB devices internally im stuck with one external USB. I might just build myself a docking station.