I recently got rid of my first copy of the 105mm f/1.8 Ai-s and picked up an amazing copy. It was used for optical measuring in a class 1000 clean room it's entire life and, once set up, never even had the focus/aperature adjusted or the hood extended. I've never seen a cleaner lens! And it came with a 5T, also not a spore of dust on it for $365. Gonna test it more rigorously tomorrow, but took some shots at the bart station tonight. Looks stellar!
f/2.8
f/1.8
f/2.8