The development phase is the most expensive phase within product life cycle. The development phase requires testing and creation of the products. Within an undergrad course that I took, we had to develop a product that fulfills a current market gap. We followed the product life cycle and the most cost came from the development phase. Our ideas of how a test would be conducted would fail and we would have to spend more money to fix the issue or to retest the creation. The development phase is very crucial in the success of a product, therefore the expenses also will be high.