For those who will use XM frequently and want a cheap, portable option, I present:
http://shop.siriusxm.com/xm/ctl10600..._reconditioned
Now the question unanswered from the site: will this deal work with the $10/mo music only subscription or the previously mentioned $25/6 month offer?
Even if not, it's a very cheap alternative to paying for XM at National or Avis, just don't leave it behind in the car accidentally.