I'd go with a cheap battery powered speaker pod.
My wife's ford escape has a typical stock stereo, is old enough that there isn't an input. I use her truck for my courier job from time to time, and found that a battery powered speaker pod worked well enough. As nice and polished as Woodtalk is, let's face it, you're listening to a conversation, not (much) Music. Do you need to put it through the stereo?
Ned