Just a few years ago, for an example, many builders looking to cut costs would skip seemingly mundane steps in building homes. House wrap (i.e. Tyvek) wasn't required by many codes until recent years. Now the technology was out there, the tests had been done, the results were clear. Building a home without house wrap properly installed GREATLY increased your risk for water damage in the future. If your curious, YES I have many examples
Now to wrap the average home in house wrap you would be looking at a cost to the builder of about $500. If you were building a $200,000 home would you like to guess the percentage of total cost? 1/4 of one percent. What about the average repair cost a decade later? We personally have seen numbers over $50k in extreme cases.
Lesson here? Don't always decide solely on price when considering a contractor. Compare "apples to apples". Ask questions. Be direct. Don't allow a high pressure, fast paced sales pitch to make you feel cornered. When you are deciding on someone to do honest and quality work on your biggest investment, do your research and decide based on the work, not the cost. As we have learned from our small example, the contractor who did the right thing may have been marginally more expensive. But how many of you are so well off that you can afford to do it twice?