The best portable DVD player, IMHO, is ...a laptop
Bigger screen compare to 7", much higher resolution (SVGA, XGA), and you can do lot of thing with it.
Its price is not too much compare to MSRP of the portable DVD which is around $700. In fact, I have a laptop HTPC forsale in classified section
He already has a laptop with DVD as do I. The laptop has very limited battery life when you are on a plane for 5+ hours at a shot and it is difficult to work and watch on the same screen. It also offers no privacy while a small screen does at least give you a small amount.
There are other reasons we don't use our laptops.
He is very serious about buying so please let me know if anyone has one for sale.
Crutchfield.com has a Panasonic DVD-PV40 Portable
DVD/CD/MP3 CD player $100 off, Now $299.95 - $25
coupon = $274.95. Get a mail-in coupon for a FREE
Carrying Case, Battery, and Noise-canceling headphones
with your purchase.
From the Crutchfield description of the above mentioned panasonic:
no built-in screen or speakers
so this would be useless on an airplane (or anywhere else you didn't have a video monitor to plug into it.)