The answer is, like most things, it depends. The average cost for billboards in the U.S. will vary from state to state. Billboards in New York will be far higher than in Idaho. However, a ballpark estimate for billboards in the Pacific Northwest is between a few hundred to several thousand dollars per month. The price all depends on key factors that indicate how many people will likely see that billboard display on a daily basis. As a rule, the more people that see a billboard the more value it has to advertisers.