Summary
There are two ways to charge $0.00 on recurring Work Orders after the initial service, which is where you'd put all the money, if that's what you or the customer prefer.
Key Points
Create a one-time Work Order with the price, create a recurring that is $0.00
Create a recurring Work Order at $0.00, edit the first Work Order and add the price
Create an initial, one-time Work Order with your price
2. And then create a second, recurring Work Order with a $0.00 price.
-OR-
Create the series with $0.00 pricing (as in step 2 above) and go back and edit the price on the first one