Help with CD player upgrade

Well, I have long known that the weakest link in my budget minded system is my cd player. And, even though it may not make sense to do (leave for college in the fall), it's either a new cd player or drugs, and I suppose I'll go with the cd player. My question is what cd player on the used market would be a good match for my acurus dia-100 and paradigm monitor 7s? I currently use a cambridge audio cd4. I don't really have a specific budget in mind, but somewhere around 500 is probably all I can convince myself is worth spending (Given that I'm a/b to go to college). Thanks for the advice, and while I'm waiting for your replies, I'll continue to try and persuade my parents to let me use the college fund for my dream system. As that likely won't happen, I really appreciate any recs. for the best sub 500 dollar used cd player.
-Ben