That's a good question! It is also a difficult one to answer with so many choices for roofing, trim, decking, railing, etc. out there in the market. This particular porch uses Fiberon decking materials (a synthetic product with a PVC wrap around a fiber-composite core), Fortress railing products (wrought iron with a hammered bronze finish) and a trim package that matches the house. The size of this porch is approximately 12' x 12'. There is another feature unseen in this photo; an under-deck system with lighting and fans to keep the entire area beneath the deck and porch protected from moisture and useable as an entertainment space. The porch portion of this project using the products listed herein would likely range in the $25-$30K range. This, of course, would be dependant upon the specific design, the choices for access and materials and several other factors indicated by your home and property (height, slope, type of materials on your homes exterior, etc.).
Hope this is helpful!