I consider myself an audiophile and I care a hell of alot about the audio in my ride.
That being said, I'm on board with the thought of you get what you pay for. I have a dual-din Pioneer head unit touchscreen that I did a custom installation with. It's got GPS, XM/Sirius Radio, USB/Ipod Interface, SD Card for updates and/or music, DVD, HD Radio, Backup Camera, Bluetooth, Handsfree, etc, etc, etc. The only reason I would upgrade would be to go for a Carputer and take the whole thing to a new level.
I would rather drop 500-600 on a name brand than a no-name chinese for half the price. Don't get me wrong, you may find nothing wrong with the cheapie ones, this is just my own perspective.
Plus I love my toys.