Hello Mark:
If you are trying to get a DVD Player for around $600.00 (that is used), then you might want to investigate getting something like a Toshiba SD-9100 (or for just a little bit more, you might get a Toshiba SD-9200 right now, since that model was introduced a year ago), a Sony DVP-S7700 (for about $350.00 to $550.00), or a Pioneer Elite DV-09 (used ones in mint condition go in the mid $600's to about the low $800's), or now, you can even get a used Pioneer Elite DV-37 from about the mid $400's to about the upper $500's. And being that you have a HDTV, the DV-37 would be one of the main players I would be looking at, if a used player is what you want, being that it is a progressive scan model. If you can find a dealer that is willing to discount, instead of looking for a used player for under $600.00, I think I would be looking to get a brand new one instead. DVD Players have improved tremendously over the last two years, to the point in which technology that was exclusive to high-end players just two or three years ago, are now showing up in newer and affordable players today. In fact, if you go to somewhere like Best Buy, right now, you can get a progressive scan DVD Player for under $200.00 (a Toshiba SD-3750 for example). But now, if I am shopping in the $450.00 to $600.00 range, then I'll be looking at a Denon DVD-2800, a Panasonic RP-91, or right now, the vunerable Pioneer Elite DV-37 (bought mine locally for $700.00 eight months ago....... great machine..... don't regret buying it either...... but now, I understand that if you can shop around on the web, you might be able to land a brand new DV-37 for around the mid-to-upper $600's).
Good Luck.......
--Charles--