1 Doing it yourself, you can build an 8x10-foot ground-level deck from treated lumber for about $500 in materials. 2  Having a contractor build it for you raises the price to $1,500. 3  You could build a treated-lumber raised deck, say 10x16 feet, for about $1,500 in materials.nd because decks are so popular, they also make homes more marketable and valuable. Here's a look at what they cost. For basic designs using the least expensive lumber, you can expect to pay from about $6 to $8 per square foot of deck area.