Paid €20 each way last time and its much better than getting the transfer bus.
We had checked in, unpacked, gone to the supermarket for some essential supplies and were on our way back to our room when the bus turned up with the rest of the people from our flight.
Same on return, receptionist called a cab, we walked outside past the queue of people waiting for the bus, got in the cab and when we got to the airport we checked in without a queue and without the mad scramble to get your luggage out of the bus.
If transfers are extra, sack them.
If they are included then fair enough, but taxis are plentiful and cheap.