PCB Boards are Cool, but the Holy Grail for robotics are the Kapton Flex Circuits which are both wire and circuit in one.
Using This Material, I was able to CNC a single-sided SMD circuit which is thin and flexible - though not quite Kapton :-(
For lightweight circuits that fit into odd shapes (like fuselages), etc, this is a process that can't be beat. You could probably use a chemical etch, but the CNC does the routing and cutout with the same tool.
First Design in Eagle then export in PCB-GCODE. I used 20mil spacing in eagle and a 16mil tool in gcode with a 3mil default (offset). I glued the scissor-cut material to a thicker PCB with spray glue, then held it down with clamps. It is critical to get the working surface flat (which took time and error).
Find more photos like this on DIY Drones
so $300 plus $40 shipping for the controller and motors
and if you want to go cheap you can build the frame for under $200
or you can check this thread or ebay item
home brew cnc start at about $2K. (About $1K for the framework/mill and another K for the electronics). I think this comes down to $1K for seriously economized models (wood frame etc...)
yes, the cnc (dremel router) removed the unwanted copper. Then cuts the part out.