What Sonically is the Difference between a $1,500 CD Player and a $10K-$25K One?

Night and day difference in sound quality , if you buy from companies that have established and  doing digital for a while 
it is like the difference of a $1k turntable cartridge,and a $5k  cartridge, realism on a much higher level. That being said as digital 
technologies keep getting better the price of sound quality has 
dramatically come down ,and there are some very good dacs out there $3k or under.

There is not.  300 bucks is tops and you will get fantastic sound.  The only important things on a CD player are:

1) speed stability (the motor), very easy to achieve with todays electronics.
2) If u are using analog outputs, the DtoA converters (may be a bit expensive for top of the line Wolfsons)
3) Quality of jitter circuits.

These are all achievable in a FANTASTIC way for under $300.

The way they sound. One of the things to consider is the system and the room. It is likely that a person owning a $1500 item may not have the rest of the pieces and a room that will let the differences be heard. Now go the other way. A person who has a setup that includes a 10k-25k player would likely hear the difference if a swap out to the lower cost one was made.

I love all the folks that assure you that there can be no difference of any import.  Try some auditioning at an audio salon, and I'm pretty sure you will then know the answer.  IME you can get some very real, sonically significant and musical improvements as you go up the food chain.  But the folks pointing out the diminishing returns with greatly increasing price certainly on to something, as well as the crazy-quick and steep depreciation of anything digital.

Get out and explore with your ears.  That will tell you a lot.

I have an old Magnavox changer with a tube output. Suits me just fine.