I sure hope he updates that auction or he's going to have a very upset buyer if they don't do enough homework to figure it out ahead of time! Yikes!
As for the game, I love it. The crane is one of the best features ever. I really enjoy the combination of flow and stop/go styles. Great art package and sounds. Sure, the Joker can takes up a lot of real estate for a toy you don't really interact with, but it's a neat feature. The Batmobile teeter-totter is a little silly, but on the other hand it adds a nice little flair to what would have otherwise just been a simple return habitrail. I've heard of people adding extra lighting to make it easier to see, which I'm sure would help. I wish they would have added a little more variety to the rules, but they are pretty cool as is.
Overall it's a fun, beautiful, unique game that seems to have gotten lost in the shuffle now. I think it stands up well even to the great Spiderman, and hope to have them side-by-side someday (with an Ironman thrown in for good measure). They would be a great compliment to each other.
$4k is probably too much for the real thing, much less for the Costco version. Mid-3s is probably more like it, but honestly they don't seem to come up that much. As for his Costco version, I'd be surprised if he got mid-2s for it unless he finds a sucker that doesn't know the difference.