Used Bookshelf up to $3k

These Fritz Carreras are worth a look.  Also agree the Reference 3a De Capo would be interesting.  Best of luck. 

https://www.usaudiomart.com/details/650241637-fritz-carrera-be-bookshelf-speakers/

I recently bought a pair of Studio Electric M4.    They are right around your budget new and they often have show demos for sale for a few hundred less.  Great speaker.   

A gently used pair of Harbeth  M30.1's can be had at or under your budget..

Quite possibly one of the most beautifully voiced stand mount speakers ever produced...

Buchardt S400 II if your room is 300–350 sq. ft. or smaller, and Wharfedale Linton if your room is larger than 350 sq. ft. I’ve owned both and can recommend them wholeheartedly.  Linton is picky on the digital front though.  If paired right, you will be paid back with nimble bass, large, tall and deep soundstage and pin-point image.

KEF LS50’s and they are no where near 3K unless you want the wireless versions. Also, a good pair of stands will be needed, and of course some high quality electronics. Amazing!

https://us.kef.com/products/ls50-meta?srsltid=AfmBOorpJiN1aM29BwUS1s_DvP1Zwhth1jV2nlJm8jykRWkfls6BJgAi

Matt M