Just a note, modern digital transmitters don't have a frequency as such, they operate on 2.4GHz but are bound so that they cant control the wrong receiver (That's the very simple version) Also, toy cars are mass manufactured bring the cost per unit down much further than we can ever achieve in a one off machine/robot.

I don't build Ants but I know they can be VERY cheap (Like under £50 easily), next its beetles where you could get one done well for £100 and then feathers where it has been done for less than £100 but ideally at least £200, excluding the transmitter.

That said, my first featherweight was £600 and was very ambitious for a first time build so you can leap out the blocks provided you have the right knowledge.

Good luck