Here's one option. Info on installation and center console removal is on that thread and some referenced threads.
The AAI-GM24 is for cars without the CD changer, and there's another model AAI-GM12 that's for use with a changer.
I installed the AAI-GM24 and it works pretty well. I think I got mine around $85 last winter. I ran some lengths of RCA-to-mini-jack cable from behind the dash. One runs out to the driver footwell and up to my music player. The other runs under the center console and through the storage bin up to a portable DVD player I have sitting ontop of the storage bin lid.
The only negatives were
- getting power to the PAC unit
- it wants line-level inputs. So if you're going to drive it with a headphone output, you'll have to run that device at high volume wasting batteries if it's battery driven and adding noise to the signal (make sure you adjust the pots on the module before closing up the console)
I can't comment on the AAI-GM12. There are also some other products out there, but I know very little about them.