the Camaro spoiler is cheaper, not "correct", but works well...it helps you steer the car at speeds over 75-80 MPH (by pushing down on front tires)
FWIW, were they available as a dealer installed option?
don't know for sure, but "probably"...as many items were...dealers like to make money , and install extra things.....I recall myself installing Pontiac TA spoilers onto Volvo 740s in the 80s, when I ran my dads Volvo dealership...LOL