My exact thought as you. I actually have done robotics research in Academia and I find it ridiculous that an arm costs as much as a car when it's just servos in series. I guess economies of scale.
Now that I'm leaving Academia I was trying to figure out how to get a robot arm so that I can continue doing stuff at home. I think an approach like the one here would be good: https://www.trossenrobotics.com/aloha.aspx. A single robot would cost 5k. You could also just buy Dynamixel servos and build it on your own, shouldn't be too hard with 3D printing ~ closer to 3.5 or 4k with that.
You could try to go cheaper by building a dynamixel servo on your own. I would not recommend this, the main difficulty is the controller which requires a lot of tuning, which is what you're paying for when you buy Dynamixel. But the raw parts of a servo are only around 50-100$ I'd guess.
Lastly any arm you build this way is going to be position control which is very different from the human arm that is torque controlled. Trying to get torque control on your arm is all the rage on Youtube these days, perhaps because the motion seems so lifelike. To do that you need to build a Quasi Direct Drive Actuator which is a BLDC servo with a low gear ratio and then try to centralize all the motors to reduce inertia. There is no accepted solution to do this, but the best results come from cable driven mechanisms like AmbiDex. Basically building a human like robot arm is a huge research problem on its own, and if you want to focus on intelligence best avoid this.
Will MKS SERVO42 going to work? Installs onto back of NEMA17 stepping motors, works in closed loop using magnetic encoder, has to be stepped but infinite rotating and $20 apiece with a motor. Latest 42D variants seems to work with CAN or RS485 too.
There is FEETECH on ali-express. About 0.5-0.25 times Dynamixel price. I've never tried it though. You're right very few of us want High Torque and High Accuracy which is the problem
Now that I'm leaving Academia I was trying to figure out how to get a robot arm so that I can continue doing stuff at home. I think an approach like the one here would be good: https://www.trossenrobotics.com/aloha.aspx. A single robot would cost 5k. You could also just buy Dynamixel servos and build it on your own, shouldn't be too hard with 3D printing ~ closer to 3.5 or 4k with that.
You could try to go cheaper by building a dynamixel servo on your own. I would not recommend this, the main difficulty is the controller which requires a lot of tuning, which is what you're paying for when you buy Dynamixel. But the raw parts of a servo are only around 50-100$ I'd guess.
Lastly any arm you build this way is going to be position control which is very different from the human arm that is torque controlled. Trying to get torque control on your arm is all the rage on Youtube these days, perhaps because the motion seems so lifelike. To do that you need to build a Quasi Direct Drive Actuator which is a BLDC servo with a low gear ratio and then try to centralize all the motors to reduce inertia. There is no accepted solution to do this, but the best results come from cable driven mechanisms like AmbiDex. Basically building a human like robot arm is a huge research problem on its own, and if you want to focus on intelligence best avoid this.