Social Media Marketer for AfterMarkett's Clients

I'm setting up a new SMMA called AfterMarkett. We have about ten potential leads already in the pipeline. I'm currently looking for an individual or team that can produce/create 1 social media post per day for these clients and can adapt for and distribute across 5 social media platforms. Please give me an estimated cost based on that and let me know if you need any more information to provide a quote, I'm speaking to a range of vendors and once I know the expected budget we'll be able to take the conversation forward. If this was to work out, the contract would be for multiple clients a month.

Also are there additional costs such as extra revisions I should be aware of?