Is it possible to find a good DAC for under $50, 000?

I certainly have been able to easily hear the difference between $1000, $2K, $5K, $8K, $12K, $17K and $22K DACs... I sure don't see why I wouldn't hear the difference in a $50K DAC. 

OP "...It’s about whether there is a point at which sensible effects cannot be discerned."

Good question. Not in my experience. I have heard well set up systems at price points out to the stratosphere... they are all very distinctive in terms of many variables. If assembled by competent audiophiles the sound directly correlates with the sound quality.

The trained ears / brain are capable of incredible differentiation of sound qualities. Audiophilia is about pursuing perfection. While the refinements may seem small, the overall impact is significant as music is nearly infinitely variable and complex (compare to a single tone).

There will always be the oenophiles and advocates of MD20/20. Although, I’m pretty sure you will not have the folks drinking MD20/20 in the gutter posting on the Wine Spectator’s forum about how all red wine tastes the same.

@celtic66 "...I own four different DACs at distinct price points and yes each improves performance measurably with the price point increase.  $300/2K/6K/12K."...

+1

I have also owned DACS from $200 - $2K - $20K. I agree. particularly when you double the price point you get a significant increase in performance. Small incremental changes in investment can just provide different but not better. I can tell appreciate a better sounding DAC... even if it its design goals are not the target sound type I want. Poor choices in your purchase and you can get a DAC with the wrong kind of sound... for instance if you like musical renditions of sound and you buy a detail scraping DAC then from your point of view, it may not sound better. 

My components are all at the $20K level. If my financial position changed and I was able to upgrade to the $40K level I would do so, and appreciate the improved sound quality. I have not gotten to the point where I can’t tell the difference between levels, what I own is financially constrained. 

I just watched a video on a guy around here that has a million dollar system. He spent over twenty years on the room and the equipment. I see him as a comrade, someone I can relate to... someone who loves music. I would very much enjoy listening to his system and trading stories about the journey we took to get where we are. I would not criticize him for being more financially successful than I have been, more dedicated to the pursuit, or somehow being a bad person because I am jealous of him. 

Thanks for bringing this excellent video to my attention.