A simple solution for robotics is Intel Euclid with an iRobot (create2,roomba).
With the Euclid, all included sensors and an iRobot, it should be possible to prepare a simple and powerful robot explorer.
Euclid: 400 $
Create2: 200 $
Tailoo USB cable
Or you can try to get this one:
All you need included.
First picures are available:
to be continued…