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

If not the Linkwitz Orion's or LX521s, or the Pure Audio Project open baffle speakers - which very few speakers can match... And I could only accept a "big name" brand (though pricey)... I would consider only the Nola speakers in your price range.  A superb semi- open baffle speaker line - which very few can match.

Nola's are very nice speakers.  Bass, go check out the Vandersteen line. If you like NOLA, then you will probably like Vandersteen too.  Lot's of cross over between the two.

Map, just because you can put expensive off the shelf parts together, doesn't mean you can make a great speaker that can honestly compete with these companies that have massive R&D behind them.  If you were to say that you make one speaker in that price range that you'd worked on for years and you keep upgrading it, I think I'd have more faith in what you are saying.  Are you a manufacturer who does this as his sold living or a hobby guy just posting on the board to drum up business?  Just curious more than anything. 

I agree with bass dude when he says at that price point, I'd stick with a big name speaker as there is no way you can ever recoup your money if you are not happy.  I've bought and sold for many many years and nothing has change in regards to selling used gear.  Big name depreciate much much less and sell much easier (since folks recognize their names) than off brands or smaller companies.  That's fact and when you are using 20 to 30k, that's a lot of money to most folks.  Take the top 5 speaker designers.  They all make different sounding speakers and they make different trade offs. There is a reason that most speakers in this price range have heavily modified or house built drivers etc...  Many enclosures are made with exotic materials as they do work better than wood or MDF etc... when used correctly.  JMHO

Since hookers and coke evidently wasn't the right answer,

I'll add that a pair of MBL 101e are listed here at $20k.  They have certain strengths that are IMO just about SOTA, but they are omnis (a plus for some listeners, an issue for others) and the low end requires a large space IMO for proper tonal balance.  Personal taste is going to drive this decision, but hearing the 101e would be a useful bit of due diligence.  If you listen LOUD, I'd say that it's a "must hear".

Marty, honest question if I may.  I was speaking with a friend two weeks ago about an MBL amp.  The more we spoke I started to remember an MBL dealer telling me that the MBL's really need their own amplification in order to sound their best.  Do you know if this is true?  They are very intriguing speakers for sure.