Since I built my first robot I learned about how much initially planned costs differ from whatever really spent to build a thing. There is nothing for free in this world: servos, motors, batteries, electronic and mechanical parts, tools to process, tools to tune, time to write a software etc. etc. So, the question is: how is it possible to claim in this site for so many robot-makers the cost of their baby building something like "20 dollars" or around? The simple China-made R/C vehicle, which can be used as a robot's mechanical base, will start up a price of robot building at least in a region of 35 to 50 USD. If you buy things separately (like motors, gears, wheels, screws etc), you earn rather in customisation according to your needs but not in a total price of the goods. Hence, It would be extremely interesting to listen to the creators of these "20-dollar" mechanical guys, how did they manage to spend so little for such the advanced toys?