Now that Skiman pointed it out, I also have a hard time finding the actual plywood wing joiner in any of the photos. Did you find that piece amongst the wreckage, if you did it looks like it probably had no epoxy connecting it to the main spars from what I can see of the photos.

Otherwise maybe the guy that built it found it at the bottom of the box AFTER gluing the wings together.....thus the $100 deal you got!

Rube