Comment by hugs

For electronics, all you really need to get started is an Arduino, 3 hobby servos, and a breadboard and wires. The first robot I sold was basically just that. And the physical parts were Lego-Technic compatible laser-cut (later 3D printed) beams. (https://bitbeam.org/, https://www.thingiverse.com/thing:11747)

Start making your own "lego" then go from there. This idea can get you pretty far --> https://bitbeam.cc/en/

This was basis of the robotics company (Tapster) that I started and have been running for over 10 years now: https://www.flickr.com/photos/68386867@N05/7855484076/