Issue 80 is/was also of higher value due to lower print run and lack of interest as the series was coming to an end.
And I should note that although Trade Paperbacks make it easier to get old stories, the TPB are also not worth much unless they are rare or non reprinted. For instance the Transformers Universe collection is pretty rare and more valueable than the MTMTE collections will be once IDW reprints them.
So issues 69-75 are pretty so-so compared to The Cosmic Carnival, Monstercon from Mars and Cash and Car-nage?
