Poster Box variations are not typically rarer than the regular non poster boxes. It was a transition that occured when the new Transformers movie was coming out, and was to help promote it. The toys themselves under went slight changes from metal to plastic parts. This is why variants such as metal toe Hot Rod & Sandstorm, or Metal front Springer had those parts changes to plastic in the poster box offers came out.

    Blitzwing with Poster Box is extremely rare. This piece seems only to be test marketed in certain area's. These are so rare, that less than a handful have been found. Some have considered them only to be prototypes which is not true. Astrotrain and Blitzwing with poster boxes are some of the rarest Transformers ever produced.

    Since I own a loose example, for once we can see the difference on the Blitzwing toy. The paint job to the face is different, as well as a hole placed in the metal under the arm.