There is a prevalent opinion in the general public that Modular Homes are always less expensive than site built homes and this is partly because lesser materials are used in their construction. This is absolutely not the case. Make no mistake any two guys in a pick-up truck can build a house cheaper than any modular home. But if you look at it from a qualitative point of view, generally modular homes by far offer the most in overall value.
The reason a modular home may be less expensive is not because inferior materials and products are being used in a modular home. The opposite is actually the case. As a whole, modular homes are built with more materials than homes that are built on site. Modular manufacturers use the same if not better building materials and products in their homes as site builders.
Cost savings are due to the purchasing power of the manufacturer. Manufacturers are able to buy in larger volume, so some real cost savings can be realized and be passed on. The cost of materials is usually commodity driven. They may go up or down according to individual markets and the law of supply and demand. If prices increase in say lumber, the manufacturer often will absorb the price increase for a time and then may enforce surcharges on when commodity prices rise faster than base home prices. Also manufacturers often also pass on saving gained through commodities in order to make their product more attractive and affordable for home owners and their builders.