I found some magnets that we are going to try from McMaster-Carr.
Ultra-High-Pull Neodymium Ring Magnet 1" OD, 1/2" ID, 1/2" Thick, 21.4 Pull lbs. Part # 3360K79
My thought is to add a small bearing in the center and mount it so that it allows the minibot to travel in the vertical plane without falling away from the pole.