Thanks guys for your help. It seems that the motors you suggested Joey are the best value, but they don't appear to have near as much torque as the Pololu ones, so I'm not sure which to get.

Looking at the pneumatics again, I found that there are quite a few small cylinders here (hopefully hyperlink worked); I would've thought that 10-15 bar would be plenty for flipping 1.5 kg. Flange looks great! I'll see if I can figure out how he did it, what parts he used.