How do I charge a booking fee each time a client makes a shift job booking request?

To access the price manager go to the "Agency Settings" under "Settings" in the main menu bar, click on the "Client" button and scroll down to the "Price Manager" tab:

To add a new price click to "Add Price"

When creating the price you can give it whatever name is appropriate like "Booking Fee" (this is just for you to see and manage, it's not customer facing), and then select the price type "Per Booking Agency Fee", put in the price, and hit "Create". 

Clients will now be charged $30 when they book!