CD Changer for A3 with factory sat nav

[Bassman]

Ok, so what's the easiest, cheapest route to go? (A3 1.6SE 2001). Where's the best location to install (boot, glovebox etc). Any tips, things to avoid etc. Had a quick look in the boot side panel (passenger side). There's a sub-woofer in there, not much room left for anything else and I couldn't see a cable ready for cd changer.

Any advice gratefully received.