I think costwise, those campers simply don't sell a whole lot which is why they are expensive for what you are getting. If more people bought them, production savings would kick in and they would probably lower in price... but...
I have found that those campers are VERY SMALL when you actually see them in person. All the camera angles, wide lens, moving shots... are designed to, well, deceive you as to how small they are.
With the "modular" "systems", everytime you want to do anything, you have lower shelves, move chairs, slide drawers, open compartments, raise roof, lower roof, etc etc. Or, many times, do it outside - whether it is with an awning over an outside kitchen (nice idea unless the weather is nasty), slide out table, movable chairs, etc.
Also, with my family, having our own bathroom was a big point. Not just a bathroom, but a usable bathroom with toilet and shower. Notice that none of those mini campers have that. They might have a port-a-jon thing under a seat, but again you have to do the "modular" thing to access it.
Just try to be honest about what you are going to be doing with the camper, and whether it will really do what you want, and whether you want to be Comfortable.
"Old man" kicking in here - when I was in high school or college, those tiny campers would have been wonderful. I could see myself traveling all over the place, towing with whatever used car I had at the time, sleeping on the side of the road. Young bones would have been fine with hard foam seats/beds that fold down. Bathroom? other side of car works fine, and could go days without a shower.
Now? Comfy bed, bath and shower, actual kitchen and table to sit at out of the weather is what I want.
Just don't be deceived by advertising. Figure out what you want and need, and find what will work for you!
