Synthetic decking comes in a range ... A composite deck with a vinyl rail system would cost $40 to $45 per ... many plastic-based deck boards and railings will ...Synthetic Decks - Consumer Watch - Consumer Reports | abc30abclocal.go/kfsn/story?id=6202029Cached[Jul 5, 2008] Synthetic Decks. Saturday, July 05, 2008. ... They cost two to three times the price of pressure-treated wood. ... Over time some of the synthetic boards can sag.