A low-frills patio or deck is pretty cheap. Everyone's definition of cheap is different, but decks can be had for as low as $1,000, according to Jessica Piha, a spokeswoman for Porch.com, a website that helps homeowners find the right contractor. But the average deck costs $8,300, Piha says.xpect to pay between $3,530 and $4,440. Don't go too cheap on the deck. If you install a cheap patio, someone could stumble on a loose rock, but at least you're unlikely to have any guests taken away in an ambulance.