I just picked up a Sony CA80ES 5 disc changer for around $350 at jandr.com. Very smooth operation, nicely built, 5 year warranty.
For around $300 you can buy the Marantz CC4000 which is also very nice. Not quite as well built, and I did not like the display or the fact you can only change 3 discs while one is playing, but it sounds very nice.