It's definitely an interesting bit of Mirage history thats for sure. By and large, the main reason for the desire (and dollar value) for the original run of Gobbledygooks 1 & 2 is the presence on the back cover of the TMNT ad (that many argue is the first appearance of the TMNT). These protos do not feature that key back cover image, front cover as well, and the guts are similiar but still different. So I can't help but wonder what exactly the ceiling on these might be longterm. No doubt with just a few copies out there there will always be demand...but I can't help but feel these are more Mirage Studios history than Turtles history, which I know are nearly one and the same, but still not quite. Theres a bunch of pre-tmnt Eastman and Laird work out there that go for comparative pennies (even though while not quite as limited as these, still with VERY low print runs) and I honestly can't help but feel that these protos are more akin to that work than the TMNT. I'm sure im in the minority on this, and I didn't want to say anything to potentially spoil the auction with my thoughts before it ended, but I just can't help but shake this sort of strange reaction I have to the book. I've had it ever since it was first offered to me and I can't quite put my finger on it.
Regardless, its an uber rare book which is still a very cool thing!
As you pointed out it may very well turn out to be more Mirage Studios history than Turtles history...but to me, it's value, not its cost, is derived from being an "uber rare" and historical piece, and that is why I believe it to be a fantastic purchase for the winning bidder.