I spend the $25 / 5 months for the music. Since I prefer not to have Google or anyone else looking over my shoulder, I use a <$100 TomTom including free "lifetime" updates for navigation.
BTW, if you call to cancel SiriusXM shortly before the 5 month contract is up, they will offer all sorts of alternatives, eventually offering to repeat the $25 / 5 months just once more. I have been doing that for several years without any problem. As I recall, in my state the $25 comes out to just over $30 with taxes and fees.
Others on this board will caution that you not give them a credit card number so they can't renew your intro offer at full price. Just post the expiration date on your calendar and take responsibility for contacting them before then and you will not have a problem. In one instance, I missed the expiration date by a few days and was able to cancel with a prorated refund based on the number of days since renewal. I was then able to renew at the $25 promo rate. They really are easy to do business with if you play by their rules. Lots of companies use promo rates to get new customers. Verizon, ATT, to name just two. In the case of SiriusXM their marginal cost for an additional receiver is nil, so any revenue they get flows right to their bottom line. Just as the airlines do, they are (legally) price discriminating, with the result that uninformed customers pay more than they have to.
KNS