Just so you know. Lifetime is the lifetime of the radio, not your lifetime!:{ I think Sirius will allow you to transfer your subscription up to 3 times for $75 each time.
I am thinking for going lifetime and been looking for any kind of discount and haven't found any.
I have head there may be some dealing room if you let it expire and then they call you with an offer. But have never talked to anyone that has actually done that.

If I find any discounts I'll let you know. Also it is hard to say what's gonna happen if Sirius & XM merge.