The knee lever adds to the value - only because they are rather expensive. If you do look for one, keep in mind that are there two styles, so make sure you get the correct one for your machine. One has a flat end (like a standard screwdriver) and the other is a round barrel with a notch in it. The round barrel ones are older and harder to find.
BTW - you did look in the case - I knew someone that didn't realize they clip up into the lid.