The set-up cost depends on the number of factors: the number of applications used; the actions used in every application; data mapping between the applications.
For example, if you need to include some specific application into your scenario, that is not listed on Zapier, that should be connected in a general way using their API.
There may be a case when an application is already connected to Zapier but the required function is missing.
Data mapping is about how the data should come from some cells and go to others. The more data and its transformations, the more time it takes to develop.
Simple automation scenario developing cost: 200€.
Medium difficulty: from 350€.