Used Martin Logans

I don't know, it depends on what model but electrostatic panels can get dirty and start arcing. M-L panels can be washed but you still don't want a real old pair. $1500 I think will buy you a 20 year old speaker, I'd want something newer. 

I dont think thin they are that good because my brother had themhttps://hushsms.xyz/

There's a lot of PS Audio gear out there, too. I think both manufacturers make a lot of gear relative to some others, but both have good reputations.

I have never been all that happy with the integration of the conventional bass driver with the electrostatic panels. There may well be a model out there that does it better than the ones I have listened to. (I own original CLS, all electrostat)