The bottom line is what are your expectations.
HD Player - Discontinued, No longer a viable investment.
DvD Player - If your not ready to jump to the Blu-ray format, You can purchase a upconverting player relatively cheap. Some benefits like the ability to play Dvix files.
Blu-ray Player - If your ready to make the jump, they will also play your DvD's amongst a host of other features. Like the ability to play Dvix files,MP4 files,MKV files etc. Dependent on brand,price etc.
Depending on your budget, You could look at some of LG's entry level Blu-ray players. IE.