I bought a 6600 when I was living away from home for three years caring for my FIL. wonderful machine. I sold it this spring for $600 which included everything including a ton of feet.
My only advice would be take it to a Janome dealer for a full service. The tiniest little problems can make a good purchase a bad purchase
I too loved the sound the thread cutter made, it sounds like the start to Pink Floyds song Money