How Much to Pay for Outsourced Social Media Marketing

I want to interview social media marketing advisors and owners of small and medium-sized businesses practicing social media marketing for an article on the costs of outsourcing social media marketing. The article has a working headline of “How Much to Pay for Outsourcing Social Media Marketing.” I will ask how outsourced social marketing is billed (flat rate, hourly, etc.), how much it is likely to cost, what kinds of deliverables or benchmarks can be used, advantages and disadvantages of outsourcing social media marketing, etc.