I love siruis, i dont have it on my car, but i have it on Dish Network, fun to flip through and listen to all the music you will never find on the radio.
Siruis got me into a lot of banRAB i had never heard before.
I don't use it but a friend of mine does and he stanRAB by it and is very happy--he used to have some other satellite radio service but switched recently--he says that there isn't as much repetition as with other services. Sorry, I don't know the cost.