You might try peeking at ebay and search for car DVD changer. I found a Hong Kong supplier (figured he was safe, almost 20,000 sales and 99%), and got a double DIN unit with motorized 6.5" touchscreen and a DVD changer.
You have two options:
The touchscreen unit WITHOUT a single DVD drive on the unit
The touchscreen unit WITH a single DVD drive on the unit
The cost for the touchscreen unit WITH single DVD and DVD changer was $725.
The cost for the touchscreen unit WITHOUT the single DVD unit was $525.
You can get the DVD changer alone for about $220 plus shipping.
(Both units also have TV)
I run all my SOUND thru the AVIC, but the AVIC screen (up top of the dashboard where friendly law enforcement officers can see it) runs my NAV (I keep the NAV DVD in there), my 12 Pioneer CD changer ($139 Etronics), and my AM/FM radio and my backup camera (which is set to auto-switch to camera when I shift into Reverse AND whenever I put on a turn signal.. I like to see behind when I'm changing lanes..).
Down at the BOTTOM of my console (where the friendly law enforcement folks CAN'T see it) is the touchscreen unit that runs the single DVD, DVD Changer and TV.
Also, another good "bang for the buck" toy is the dual headrest screens. I picked up a pair of pre-built headrest screens 9" made by Sharp for $299, that use the wireless headsets. If you have removeable headrests, you remove them, put them in storage, and replace them with these units, and the wires are pre-run down thru the poles that hold them in the seat. Fish out two power wires from one pole, eight audio (two in, two out) and you're all set.
My installer guy setup the car so that there's a "switcher" by the driver, and on the outside pillar near the two headrest monitors. The switcher has ONE button and 4 LED's. You can switch to:
1) Nav
2) Backup
3) Single DVD
4) DVD Changer
If I'm watching a single DVD the guy in the backseat can change DVD's on the changer, OR bypass the switcher and put in a DVD of their own in a single DVD player/TV tuner setup under the seats of each headrest.
We've already installed the Cell booster w/external antenna, and the 5KW AC inverter, still have the CB (keys 80w), 1.2K amp to go. I'm still trying to cogitate btw single and co-phased (dual) antennas..
Q: Where do you get the power?
A: My car guy installed two 1200A/12VDC dry cells in the back of the Tahoe. I call these the "toy" batteries that power the "toys" (like the 5KW inverter and soon to be installed linear amp). They auto disconnect from the main battery when the engine shuts down, so if I'm playing with toys with the engine off, I can't drain myself down to being unable to start the car. The relay reconnects at 15mph to recharge..
Q: Why such a big inverter?
A: I'm a musician, I only do theatre pit orchestra, and some of the gigs are summer amphitheatres. Power gets hinky at some of these facilities, so I can plug in my keyboards/amp, bass player's amp, and the pit orch music stand lights from my car if things get crazy (only once this summer so far!). It's nice to have around.
All my best,
musikman1