Best full range loudspeaker for the used price of 10 to 13,000 dollars

Sonus Faber Olympica IIIs,as others have mentioned, are a really special loudspeaker system when used within their design parameters. Give them what they need to sound their best... and magic happens with a flick of a switch.   

@cap,
I was disappointed in the Dynaudio Contour 60 demos in the 3 room. Most of it was too loud. In one room, I requested for the volume to be turned down and they seemed to loose that magic when turned down. Also, when these were driven by a pair of Mark Levinson monos, they sounded very good (but too loud), but anything less might not work that well. This is my take of the demos.
On the other hand, the TAD Micro Evolution One defied their size. The Salks were also very nice sounding loudspeakers, driven with low wattage amps. One speaker that really wowed me was the Kii.
I completely agree with you on the Magico and YGs - looks like our experience mirrored w.r.t. these 2 brands.

My solution was a Dynaudio C2 with a big REL sub.

I think you are better off find a used pair of Sonus Faber Elipsa SEs over the Olympica III  (not the regular elipsa).  A much better buy and the used price will be around the price of the Olympicas.   I have owned both.   Feel free to message if you'd like.   

At your price-point, you should be able to demo speakers at home. You won't know if they satisfy you until you hear them in your own environment.