I have extra filters I ended up not using in my K3/S so they are for sale:

2x 7-pole 200Hz Elecraft KFL3A-200 filters, the offsets appear to be matched: asking $75 each, shipped.
7-pole Elecraft KFL3A-500 500Hz filter: asking $75 shipped
8-pole Elecraft KFL3A-1.0K 1.0KHz filter: asking $105 shipped
8-pole Inrad #718 for Elecraft, 1.0KHz filter: asking $105 shipped.

73, Paul, W6IBU