Not quite in the realm like the $50 to $90 'Google Voice / Google Vision AI' kits
Regarding the price, the actuators seem to be ~240USD. A good stepper motor with the appropriate feedback mechanism to make it suitable for servo-like control plus a modern stepper motor controller that is suited for the robotics context will likely not be (much) cheaper and you have to hack together the servo functionality, tune settings, etc. - which seems detrimental if the goal is repeatability accross teams. I'm not in the target audience for these robots either but from the perspective of robustness and repeatable research they don't look too shabby.
Examples of cheap sensors: MEMS microphone, camera, voltage sensor, mass sensor, distance sensor, multi-axis position sensors (gyroscope/magnetometers).
Examples of effectors: Any kind of motor, solenoid, LEDs, etc.
If you want to constrain the question to 3D motion, here is a suggestion - hack the controller of any existing RC car platform. Add overhead position sensing within a fixed arena added via external camera. Maybe add a MEMS microphone (USD$3) or position sensor (~USD$10) to verify airtime/orientation. ML problem #1: Add a ramp. Try to get it to jump highest (longest time airborne). ML problem #2: Same with a power efficiency metric. ML problem #3: Same with a time efficiency metric applied to navigation from a random start point and orientation. ML problem #4: Motor noise vs. jump height optimization.
my experience has been everything < $1K uses crappy servos.
The total cost for one robot was well below 1k. The servos are $25 each (Turnigy 306G if remember correctly), all connecting parts are 3d printed, the electronics and batteries are about $50, and you could add a raspberry pi for $50. So in total <$500, depending on number of DOFs.
Of course, these servos don't have the same torque as Dynamixles, for example. But they are lighter!
Unfortunately at that price it comes without a manipulator, but I have bought (very) cheap arms and will experiment with them soon.
is anyone aware of an open-source alternative to these servos? this would be a great contribution to the community, if not available already
But for some reason, most projects I found do not use DC motors:
If you ever find a good OSS servo, could you ping me?