Best entry level audiophile CD player with Co-Ax

I have a Peachtree Decco 65, and old Paradigm Compact Monitor speakers and need a CD player with co-ax and optical output.
What would be the best entry level CD player I could buy used for under $500?
Sigh...there is no "best" of anything at any price level. There will be plenty of opinions of what folks think is best for their ears in their systems, in their rooms. This will have no impact on what will work best for your ears, with your gear, in your room.

Sorry, but if you want others to help you, you need to help us first. What type of sound are you looking to achieve? Are you looking for a CDP that is highly resolving and accurate? Or are you looking for a CDP that is musical, with warm timbre? No, they are not one in the same, and no one player does both well.
If you are using the DAC in the Decco unit, I would purchase a new budget CD player with warranty. (most have digital outs) I believe Cambridge, NAD, Onkyo, or Yamaha would fit the bill. If you want a better used CDP, I would strongly recommend the Rotel 1072.
the emotive erc-2 is in the price range, is well built and has strong reviews about sound quality and buyer satisfaction. who else gives a 5 year transferable warranty with 60 day return? I have one and it sounds pretty good compared to my 1900 dollar arcam. good luck.
The Marantz CD7004 fits the bill well. Check out the review in Stereophile. 3 year warranty.

Since you're specifying digital outputs, I assume you don't really care about the player's D/A and analog section; so the player's "sound" is irrelevant. You just want a reliable transport.
I've used the Onkyo C-7030 as a transport for over a year and it hasn't mistracked yet. Heavy and good looking too:

Under $200.
As stated previously, it depends on how you plan on using the CDP. If as a transport I concur with Mik971. I would also consider Marantz, though you might consider the CD5004 over higher priced Marantz models. Check into it, the transport mechanism may be the same.
TEAC is still making CD players and is the company behind Esoteric you may want to check out their basic units for transports. Philips may or may not be still making good inexpensive CD players I have been using one for a while now its been very reliable.
A little more sophisticated up the food chain are the Hi-Fi Chinese units like Music Hall and many others which will cost you about $500.