Speaker selector app.

These Acoustic Zen Crescendos will get you pretty close at a little over your price target...

https://www.usaudiomart.com/details/649526567-acoustic-zen-crescendos-mappa-burl/

Or these Nola KOs if you can pick them up local...

https://www.ebay.com/itm/123791631135?ul_ref=http%253A%252F%252Frover.ebay.com%252Frover%252F1%252F7...

Or Joseph Audio Pulsars with a pair of SVS SB2000 subs for about $5600...

https://tmraudio.com/speakers/bookshelf-monitors/joseph-audio-pulsar-bookshelf-speakers-gloss-black-...

https://www.svsound.com/collections/2000-series/products/sb-2000

If a true 20Hz is a must have you're pretty much gonna have to employ a sub in some fashion at this price level.  Good luck with this. 

I think something like that would be a great idea, maybe taking in all the pro reviews and online reviews and condensing them into a relative selection of speakers with sound characteristics and prices. It would also be nice to have a wide selection of speakers so you can discover models or brands that you may not have heard of before. 

We have aps that do that for hotels, airfair, car rental, car sales, just about everything. 

So calling on all programmers get out there and build an app that condenses all the audio websites information and data bases into one app. GO. ...

With the new D7.2’s now announced, new Spendor D7 can probably be found for $5k-5.5k but they don’t play to 20 Hz (upper 20’s). I pair mine with REL S5 and sounds great but you won’t quite be able to get there at 6k. Maybe $7k though???

You need lots more money for that kind of speaker and then a lot more to properly drive them

Goldenear will get you most of the way there.