These were standard on all 2009-2010 Vibes, so the previous owner of your Vibe must have misplaced them or something. They are also the same on all 2009-2014 Toyota Matrices.
Car-part.com can help you find Vibes and Matrices in junkyards near you where you should be able to score the dividers for cheap as MacGyver mentioned.
For reference, the GM part numbers are; Front separator:
#19184894 | Rear separator:
#19184893