Ron above nailed it.
Used motorhomes have different issues. The first is how the previous owner cared (or neglected) it. If the rig has sat out for years, the generator's carb is going to be shot, the tires likely will need to be replaced due to rot, the fridge is going to have entire civilizations of mold/mildew growing in it, and so on. A rig can be a top tier model, but if a window was left open and the floor is rotted, it might be worth scrap, if that.
Used can be pretty tough. First water leaks. If there is delam, bad smells, rotted/soft floors, or discolored/warped walls, run. Fixing cabover rot will be more expensive than pulling and replacing a dead V-10 and transmission.
If used is affordable, go with it... but be very careful, and buyer beware... RVs are not used cars, and there is no such thing as lemon laws. In fact, assume all used rigs are lemons until proven otherwise.