I have a spare kit with a original Jefa rudder gaiter, as described here:
http://www.jefa.com/products/sealing/sealing.htmThis is for a 100mm diameter rudder tube and 70mm diameter rudder post. Complete with matching hose clips, as supplied by Jefa, in sealed original bag. The outside and label have gotten wet in storage, but the bag is still sealed.
Jefa charges about 60 EUR for it (with Danish VAT at 25%), I'm asking for £30 plus shipping.