The problem may just be the wages when they are so low in the construction industry. It is sometimes backbreaking labor and much harder than the $20/hr job at the convenience store or local McDonalds. This is probably the reason they have to go with illegals rather than local citizens. If they paid more they may get citizens but make less money. The product will sell for the same because the product is what people are buying not the inputs for the products. The use of illegals is mostly for reasons of the marginal profits for the company.