Fair price for 2012/2013 Trek Madone (Dura-Ace, carbon, 58cm)?

Hi everyone, I’m looking at a used Trek Madone, likely 2012 or 2013, size 58 cm, carbon frame, blue, with Shimano Dura-Ace.

The seller calls it a “Madone SLR,” but I think it may actually be an older Madone 6/7 Series from that era.

Details:
– Carbon frame
– 58 cm
– Shimano Dura-Ace
– Used condition
– 28" wheels

+ Additional Fulcrum Racing Zero included.

What would be a fair price today? Would 500USD be a good deal?

Also:
Is this likely a 6 Series or 7 Series?
What should I inspect on a 2012/2013 Madone (BB90 bearings, carbon cracks, seatmast, rim brake wear, drivetrain wear)?
Would you still buy a 13-year-old high-end carbon road bike today?

Thanks!