I think these "Truck Conversions" are really super C's. Whether its a Class 8 or a Ford E350, class C's are all built the same way. You get a chassis with nothing on the back and a full cab on the front. The manufacturer just builds the coach. It really comes down to price.
You have the same problem with class A's. Some gassers can be bought for less than $100,000 and some cost over a million.
The problem is the owners. An owner of a RV that costs over $200,000 is a bit different than someone like me, who bought an old piece of junk for $3000.