Of all the phases involved in the product life cycle, as others have stated, the planning and development stage would seem to be the most expensive. During this stage in the product life cycle, the company is constantly working to make their product unique and fix any issues that arise. This is more cost into developing the product. The product will typically more than one try to create the final version. As a result, the product will need to be constantly redone and fixed until it fulfills the needs of the customer and the purpose the company intended. There is also the issue of making sure the market is at a good spot to release such a product. There is more money involved in the launch, to make sure that the product is advertised properly and becomes a success.