At that price, you can get most head units...unless you are trying to buy them at a local store.
At that high of a price, you'll have to narrow it down even more, as you get a lot more for you money than you could have just a few years ago. What else is important?
do you want to play CDs?
do you want to play DVDs?
aux and USB in the front or at all?
How many file folders would you have on one storage device?
video play back
full color?
wallpaper display
are you going to use an amp? (some units have better internal amps than others)
Detachable face (I was suprised that today that not all 1-DIN units have a removeable face)
Subwoofer level control?
Bluetooth
Sat radio
Illumination colors
My favorite right now is the Kenwood KIV-700, but has no detachable face, no disc player, and no blue tooth. But the intuitive controls, high choice of illumination colors (green for my car), easy to see and navigate screen, quick access to the subwoofer control, and being USB hub freindly, made it top of my list. The non-detachable face is the only thing holding me back from buying it.