I'd suggest an alternative. Hunt down a used laptop computer with a DVD
player.In the Mac world for instance you can get an iBook with a 12"
screen (new mind you) for $999. Comes with a built in battery (unlike
at least one of those units you posted on). Larger screen. Can do other
things than play DVD's too.

I'm sure there are PC laptops similarly priced. If you get a used one
(aka older model) the price is likely to be less and potentially down
in the price range of those purpose built units, or only slightly more.