PM verslagen1. I got one from him and he had a couple more to sell.
Pretty easy to re-key your self or make it so it doesn't need a key.

You know you can take the tumblers out of the lock if the cap is off the tank.   No one but you will know your fuel cap can be opened with "any key".   So , you don't need a key fitted to the cap anymore .  

Its just a simple mechanical device …  

Have you checked at AutoZone for a generic one ?

You should add
That's a PDF.