That's an interesting floor plan, one I don't believe I've seen before, which would lead me to believe it wasn't very popular, which would naturally affect it's resale value.
As far as bunk beds, I believe you find them mainly in travel trailers. In your case I don't see where you'd need bunk beds. A more "common" Class C would have enough sleeping spaces without the bunks. Typical is the large cab over bed along with a sofa/bed, a dinette that converts to a bed and a bed down back. That would give you an extra sleeping space, or one for each of you.