Best CD player under $500 used?

I'm not sure what sort of electronics you are going to use your CD player with; but would highly recommend the Music Hall MMF CD-25 CD player. Unlike a number of the other units mentiones above; this is a current model CD player. Has decent build quality, provides very smooth yet detailed sound (which improves with time) right out of the box, has HDCD decoding, and operates very quietly. With a little shopping here on Audiogon, you should be able to get a demo unit or a little used unit in your price range.
Also, when you get a chance - upgrade the stock power cord. It improves the already decent sound even a bit more. I did so a week ago and am delighted that I did so.

How about a NEW NAD C541i for $400?

HDM, would you recommend a DAC with the Philips, and, if so, what would you recommend?

Thanks

Rich: I have no experience with outboard DACs at all so am in no position to recommend one. Just to clarify things, I'm using the RCA with its own 24/96 DAC, nothing outboard, and the guy using the 963SA was using it with its own DAC as well.

I just added a new NAD 541i to my system a couple of weeks ago, for about $410 US. It has 24/96 Burr-Brown D/A chip, HDCD, remote, digital out, etc. and sounds great IMHO.