This is Stair Bear which we (my kids and I ... ok this one was mostly me) built for the ServoCity + Actobotics Stair Climber Challenge. As it turns out we won 1st place! In the linked Instructable, I show you how to make a very basic stair climbing robot. Improvements could be made for sure - for example, this version cannot steer, has no sensors, could be faster, etc.
(ServoCity.com Parts Only)