Looking for a diff drive / skid steering dev platform

Hi /r/robotics!

Do you know any diff drive or skid steering mobile platform that are good for development? My main requirements are:

• Good motor + encoder combination
• Capable of carrying up to 4 kg of extra payload
• Ideally some ESC/motor driver that can be reasonably well interfaced to something like arduino/Raspberry Pi
• It would be good if it didn’t cost fortune

My main goal is to have a solid development platform that I can use for testing out sensors and algorithms in ROS.

In case there is no such platform available can you recommend a motor + encoder + driver combination? If there is really lack of such robots then I’m willing to make one and open source it.

Thanks in advance for any insights!