1 Prices for underground sprinkler systems vary considerably by region and climate, but for an average 2,500-square-foot (50-x-50-foot) front yard, it's about $1,500-$2,500, while a sprinkler system for 5,000 square feet (front and back yards) costs about $2,500-$3,500. have just received two estimates for a sprinkler system at my new (as of Oct. 2011) residence. House was built in 66 and new had a system. 1st quote seemed high at $6,000 then I got the second one for $10,000.