6 months is a doubling of the original 3 months they used to offer - probably a sign that they aren't as popular as they hoped to be.
I like Sirus because Pittsburgh radio sucks. When it comes time to renew it, the car saleman told me when they call just say that you are dropping it. each time they call they will lower the price. It takes a little work but you can drop the price to 25 dollars for 6 months.
I like to listen to 60s on 6.
Call Sirius Just before the subscription runs out and tell them you want to drop service. They'll tell you they can get you a deal, and they will, but don't take it. Tell them you are willing to pay just 4 dollars per month. They will come back with 5 per month for 5 months. Been doing it for a long time now.