The Mfg per unit cost is based on how many units that they make. I would guess that RV mfg is on a 85% learning curve. In simple terms every time the number of units doubles it takes 15% fewer hrs to mfg the unit. If it takes 1000 hrs to make the first unit the second would be 850 hrs, the 4th would be 722 hrs and so on. The Mfg that builds and sells the most units that are the same would be able to sell the units cheaper and make the most profit. If they plan on building 1000 of the same units the 1000th unit would take about 440 mhrs to build, they would price the RV according.