It really can't be all that difficult to make a new Push-like device. All it takes is a standard remote controller like what is used for radio controlled cars plus a separate radio link for the voice portion. The mobile end would be pretty standard too, with two independently controlled drive wheels (plus a couple of outriggers) that will enable it to go forward/back/pivot. Stack a couple of batteries on top and add the radio receiver and speaker for the voice and you're done. Finish it off with whatever "personality" you'd like to give it; a trash can, a potted plant, R2D2, etc.