If you travel to Granada by train, be advised that the bus route numbers have changed radically. And, judging from my experience so have some of the actual routes. Do not go by the RS tour book. Check for the tour book updates and even download a bus route and schedule from their website if you can.
FWIW, two bus tickets were about 3 Euros. For 7 Euros we had a taxi take us to our hotel after giving up trying to find the proper bus stop.