The piece of string question...
In theory I charge the planning/strategic part of the team out at £500 per day.
In practice this will vary depending on the complexity of the job and the longevity of the relationship. We would rather have a retainer for say six months than carry out and price up lots of separate jobs that added up to more, but mean I spend my whole time monitoring, measuring and itemising each individual length of time we spend on any number of projects.
In truth each campaign has a value to our client and they pay us what that campaign is worth, rather than piecemeal for its constituent parts.
We do not mark up third party costs and often have our partners or suppliers invoice clients direct so there is absolute transparency in the financial arrangements.
Once we have discussed what you need, we can give you a firmer picture of the likely costs associated with the work in detail for the finished job.