Do the more expensive DVD players make home theatre sysems sound better than the cheaper DVD players?

Be carefull, don't paint yourself a target.
Sometimes a lack of responses speaks volumes.
Your question is too open ended.
In other words, do your own homework.
Be specific, give us 2 brand names, not expensive vs cheaper.

That being said, In my opinion, the more expensive units "usually but not always" means better reliability, quality, "probably" tech support and "maybe" an easy repair and or replacement policy.
Cheaper "probably" means none of these, in which case, buy another one you cheap......

well i dont use really expensive dvd players, for that matter i dont use progressivescan either. i use a dvd player and output 480i to my scaler and let that do the conversion to the native resolution of the display or projector. with blue ray or hddvd i will use native resolution

ed

ed you changed your byline.
I think "Hire a Pro" is better I never understood the corn eating part.

Yes, you do pay for quality. Better processing (both audio and video), better DAC's (of particular use if you have lousy DAC's in your pre/pro and therefore want to use the analog out's), SACD/DVD-Audio capabilities, pro-scan, etc. Heck, cheap DVD players often won't even process DTS.