A cheap option is one of these sainsmart 6 axis robot arms: https://www.amazon.ca/gp/product/B00UMOSQCI.

I haven't documented anything yet, but I got the arm working with ROS/MoveIt! for kinematics. The code is here: https://github.com/lukeinator42/sainsmart_arm_ros. It uses cheap servos though so I don't think the accuracy is near 0.25mm.

Here's a video that shows the arm in action: https://www.youtube.com/watch?v=Yi_QydaN-34

I'm currently also building a Roboteurs RBX1 Remix arm that uses stepper motors, but it's not complete yet.