You may be right, but to be able to do that you need to be an experienced roboticist. I am sure I can build the parts and assemble the thing, but it will be something like Lynxmotion's humanoid robots. The cost of parts only could get up to about $300-500, depending on servo quality. To make a servo controller is not such a big deal, but to program the micro used for that to generate simultaneous moves with all servos is not so easy.
Now the Bioloid system features special serial I2C servos, more powerfull than on any other humanoids. They have a micro integrated in them able to provide feedback to the central micro, like position, load, temperature, speed. The serial speed runs at almost 1Mbps! And it has a nice servo controller based on ATmega128. I don't think you'll be able to replicate that. This is why I asked the question... If you would have said that for any other humanoid, I would have not commented it...
But it is true, you can build a humanoid robot with a $200-300 budget, a lot less that the Bioloid's $869 on the Trossen Robotics website.