Did it guys...
Just filed the dispute this morning and wasn't asked yet to make some "deeper" comments on the nature of the transaction.
We'll see how this is going on. Seller has time now till June 4th to react.
I checked the laws (asked a friend of mine who is a lawyer) for owning/buying/selling a rep in Germany too. As long as it is only for private reasons it is allowed within Germany and so I guess not that much of a problem for the whole EU.
It is prohibited to import a rep to Germany via mail...it is allowed to do it personally (e.g. getting back from a trip to China and having a rep with you).
It is prohibited to do business with reps (buying and/or selling to make a profit), but it is allowed to repair/mod them as a watchmaker, even though he makes some profit with it (as long as he is only doing the work and the parts are provided by his customer).