The cost of hiring an SEO agency can vary significantly depending on several factors. Typically, the cost ranges from $2500 to $10,000 per month, with smaller businesses paying less and larger enterprises paying more. The size and complexity of your business, the scope of the project, and the agency's experience and reputation all influence the final cost. For example, smaller businesses may pay around $500 to $1,000 per month, while larger businesses may pay upwards of $5,000 to $10,000 per month.