Just sharing my Linorobot project. It’s a suite of ROS compatible ground robots that support 2WD, 4WD, Ackermann Steering, and Mecanum Drive. I hope this can be useful for those who are looking for a low cost alternative in building their robotics application. The design’s pretty flexible so you can start prototyping with a small robot and scale it up to carry much payload later on. It also supports a variety of accessible sensors (depth sensors, lidars, IMU) .
You can check out the project page here: https://linorobot.org