"I was thinking before, that I could get the Magnepan LRS, new and a good subwoofer..."
That would be a better route to take assuming you also get an amplifier that drives them close to their potential. As for Martin Logan panels, in my experience they last much much longer in terms of their sound performance if they are cared for properly by their previous owner(s), e.g., exposure to direct sun, smoke, dust, humidity, etc. I have a pair of ~20 year old Aerious I model speakers and they (still) sound very clean, crisp, top to bottom. Same consideration for amplifier choice applies to Martin Logans as well. My suggestion is consider your total budget and divide it between speakers and the amplifier/preamplifier, source component, cables, etc., etc., accordingly.
Good luck.