Why are teardrops so expensive?

I met a couple in a campground a couple years ago that had a teardrop that was a real road ( and off road ) warrior. The sides of it were all scraped and scratched, and they related some of the stories of serious off road camping they had done with the little rig. They loved it, and I could sure see the appeal of having one for some fun boondocking. It was obvious that little camper had some stories to tell.
I can see why they cost a fair bit....the labor expenses in building one is likely very similar to a bigger unit, and there is also probably pretty close to the same material costs.