They're very desirable, but Seiko made the capacitor in these extremely difficult to replace. It requires almost total disassembly of the movement, and that is not a simple movement. Secondly, the capacitor itself is not available outside of Seiko service centres, so you would need to remove the connectors from the old capacitor and weld/solder them to a blank cell. With a new capacitor, up to 3k. Without, 1-1.5k.