Then I found this:
It's a Disney Infinity figure for video games. It cost me $14. As you can see, it's pretty damn big, those are a Knight Models Doctor Doom and Eureka 28mm Modern next to it. Now, in the film, the Hulkbuster is a little taller than the Hulk, and my Hulks (I have a Hulk problem) tend to top out at about 54mm, making this one damn big Hulkbuster. It's a bit hard to see in the blister packaging (I'm keeping it sealed until I decide to keep it), but it's about twice as tall as the KM Doom.
Now, in World War Hulk, Iron Man breaks out a new Hulkbuster that's a fair bit taller than old Jade Jaws; Heroclix make one of those too, but it looks pretty naff and would be upwards of $50 again. So what if I called this big boy the latest model? As you may be able to tell, he's pretty nicely pre-painted and shouldn't require much work to get to a tabletop standard.
So, true believers, what do you think? I'm going to base my decision to keep it or return it based on the feedback I get here.