Recently I bought someone a CD based mp3 car stereo as a gift. It's a Rockford Fosgate something or other and IMO it's a complete pile of crap! No IDx tag support, instead it uses ISO9660 filenames and scrolls them across the display. Song navigation is near impossible and the display lights up like a christmas tree on acid! In truth mp3 was an afterthought or more likely, hardly thought about at all!
Slightly on the plus side (compared to the examples you gave) it stores on average ~100 good quality mp3's on a CD-RW.

All things considered though, it makes a 2nd hand empeg @ $500-$600 look like even more of a bargain