It helps a lot if you own many many things that you got out of old electronic devices. I used motors from old XBOX gamepads to make the robots shake ... and move. I used old motors from useless floppy disk drives to build a the crawler.
out of old pc mainboards I got battery holders and 3V button batteries. Also LEDs or resistors could be sourced out of old electronic parts.
To make the radio controlled mover I bought a bunch of radio controlled mini cars. I got 27Mhz and 40Mhz cars so that I can guide two robots at the same time.