What used speaker would you buy with $20,000-$35,000 and why?

Great answer.  I agree with value per dollar, however being audio, the real question becomes which speaker will sound BEST in your system.  When I said Vandersteen or other names speakers will keep their value, that doesn't mean they still won't be the best buy for you.  Taking into consideration that they well may be the best sounding for you to begin with.  If so, then that's the speaker for you to get I would think.  The fact that they will cost less in the long run if you need or want to ever sell them again in the future.  The bottom line is that for this kind of money there are so many good options.  You really need to drill down to see which speakers you want to audition based on what's around you to listen to and if there is one or two reviewers who seem to listen the way you do and appreciate what you like to hear.  That way you don't go crazy like I did (although I'm glad I did and it was a fun two year journey getting to Vandersteens, which I went into my search not wanting at all).  Companies change their sound greatly over time with new components to work with and new parts as well.  I listened to so many speakers from the 90's to current and most of the speakers who's parts are over 5 years old, on the whole, didn't sound as good as more recent designs etc...  JMHO.

I'd travel to CA to visit Teresonic and listen to the Ingenium. Why? Because my next stop on this quest will be a true single driver speaker system.

Personally I think what you spend DOES correlate to enjoying the music. If it didn’t, most of us would be content with the all-in-one boombox on a shelf in an ’entertainment center.’

MD, sometimes it matters.  Just depends as there are sweet spots in lines that make a ton of sense.  Then when you are able to properly mate these, that's when you get a value.   I've heard plenty of one driver systems over the years. That was the first thing that stood out to me about the Vandersteen line.  They sound like a single source speaker.  Very few do this for ME.  I am very sensitive to distorted highs and coherency.  That's why I've yet to hear sub systems that I truly love and would want to live with.  Balance is too important to music for me.  If it's not balanced, then I keep thinking while listening.  Takes away the fun for me.  Most of the lines I"ve liked in the past and present are first order cross over, true time and phase aligned.  The only built in subs I've liked are the Vandersteens since he's found a way for my main amp to keep it's 'sound' even on Richards subs/amp.  It's also nice to be able to tune the bass for the room I'm playing it in.  That's always the hard part, getting deep, tuneful bass AND loading the room properly.  I personally feel the Quatro is the best value in his line.  As I said, I'll be selling my Treo's to get the Quatro.  His speakers sound great on zero feedback SS amps and sound even better with tube gear if you want to run tubes.  Sorry to go on and on, but I"m listening now and have been for hours.  Just realized I need to head down to eat, lol.  Keep us posted on your search.  This is fun. Thanks 

MD, sometimes it matters.  Just depends as there are sweet spots in lines that make a ton of sense.  Then when you are able to properly mate these, that's when you get a value.   I've heard plenty of one driver systems over the years. That was the first thing that stood out to me about the Vandersteen line.  They sound like a single source speaker.  Very few do this for ME.  I am very sensitive to distorted highs and coherency.  That's why I've yet to hear sub systems that I truly love and would want to live with.  Balance is too important to music for me.  If it's not balanced, then I keep thinking while listening.  Takes away the fun for me.  Most of the lines I"ve liked in the past and present are first order cross over, true time and phase aligned.  The only built in subs I've liked are the Vandersteens since he's found a way for my main amp to keep it's 'sound' even on Richards subs/amp.  It's also nice to be able to tune the bass for the room I'm playing it in.  That's always the hard part, getting deep, tuneful bass AND loading the room properly.  I personally feel the Quatro is the best value in his line.  As I said, I'll be selling my Treo's to get the Quatro.  His speakers sound great on zero feedback SS amps and sound even better with tube gear if you want to run tubes.  Sorry to go on and on, but I"m listening now and have been for hours.  Just realized I need to head down to eat, lol.  Keep us posted on your search.  This is fun. Thanks