With adjustable coils I have always just taken the adjustments as two settings. Full soft, full hard. Unless you have some absolutely fkn awesome coils everything in between is hardly noticeable. The difference between 16 clicks and 12 clicks isn't going to be a large enough difference to satisfy your desire for more comfort.
If these coils were in good shape they could sell for 5-600. They look pretty rough though. I'd say 400 as is is fair. Even if the car had low miles that's not to say the owners didn't grab them used off a forum. The coils in the picture are caked up with dirt pretty badly too. IMO that wouldn't happen in 5,000miles, atleast on a car that was looked well after. Granted, if the car is in an area where there is snow and dirt roads it could explain the dirt, but then it begs the question how much does snow effect a steel bodied coilover? The coils on my car have like 30,000 miles and they are no where near that condition.