I had a local car audio place throw in a very basic Kenwood deck.
I had the standard head unit, with nothing fancy (infinity/bose/whatever options)
All I wanted was to be able to talk hands free through bluetooth, so that was the only feature I really targeted in my search.
I think I spent about $120 on it including install(free). Only thing they installed was the head unit, they left the factory speakers/amps/whatever alone and connected to the factory wiring with a simple plug adapter.
The funny thing to me is that this is the least I have ever spent on a car stereo with the simplest install (no re-wiring), and it is easily the best sounding car stereo I have ever had. Sure, when I turn it up to super squelch territory, sound quality goes in the crapper, but I don't want to be deaf anyway. My volume control goes up to 32 (I think), anything 28 or above starts getting distortion/clipping, comfortable listening is 15 to 18 normally for me, 22 with the windows down.
I used to be a big Pioneer fan, the last model I bought of theirs was one that DIDN'T tout the use of mosfets, and it sounded like absolute garbage. I thought it might just be that head unit, so I returned for a new one at the store, same thing. I ended up returning again buying a kenwood (no mosfet either), and it sounded a little better, but I think I had crummy speakers (precision audio). That was back in my dodge neon in college, sounded ok for all of $300 in speakers and head unit.