Bellabot[0] comes to mind, there's also a startup doing Roomba-like bot that magnetically dock to specially designed shelves. Though, they don't sell for $250, so actual Roombas and ROS mods for "hoverboard" Segway clones[3] might be more cost effective.

0: https://www.youtube.com/watch?v=l1hQ5YTMJEw

1: https://www.youtube.com/watch?v=SdVglHOJgiA

2: https://github.com/hoverboard-robotics/hoverboard-driver/tre...