I received a letter in the mail today from Sirius XM with an offer for 12 months of service for $5 a month, plus a free 4th gen echo dot. I had just renewed my plan back in april for $5 a month, but I chatted with a rep for a few minutes, and they were able to apply the offer to my account, which extended my subscription for 12 more months, plus the free dot.
I assume this offer is valid for everyone, but am setting it as YMMV just in case. If you are trying to just get the Dot and do not care about the service, I am not sure if this deal is for you. You may be able to cancel service after you receive the code, but I am not sure.
However, for people who actually pay for the service, this is a great deal, and the free dot makes it even better.
SiriusXM Music & Entertainment