Choose a seasoned deck builder (a contractor) who has a good report with the Better Business Bureau. You want the contractor to be able to tell you what he needs for a certain size deck and quote it as a package. Decide how large you want the deck to be. The economical deck is the on-grade deck. It's built next to your home just above ground. You don't need steps, posts or rails, so this style of deck offers significant savings in materials. Get your contractor to quote a turnkey job on paper. This includes labor and materials.
Take your contractor to the home building supply and purchase all the deck materials needed. Another way to save money is to use treated lumber instead of vinyl decking. According to Luma Garden Structures, vinyl decking is twice as costly as regular treated deck lumber. So make sure treated lumber is in the quote.
Buy sealer to put on the deck when it is complete, to protect it. You'll need to repeat this about every three to four years. When the deck has been sealed, enjoy your barbecues and family time in your outdoor room.