If the lens is indeed in a "as new" condition, it seems to me you got a great
deal! An international Leica dealer here in Holland is selling one in "as new" condition for â‚¬1190 (AUD 1714), but you'd have to pay all kinds of taxes and higher shipping charges. I can find a 50mm Summarit for â‚¬895 (AUD 1289), but you have to keep in mind that is significantly slower. I'd pick a Summicron over a Summarit any day (and then I would and have pick(ed) a Summilux over the Summicron
The thing with Leica lenses is that many of them do not go down in price much, so even used lenses are expensive. For some, you could even sell at a profit shortly after purchasing them, because buying them through a store or Leica involves (long) waiting lists.
The only problem might be that the lens is not in "as new" condition (it's impossible to tell from the pictures). A scratch on the front or rear elements, or improper alignment can force you to send it back to Germany for repair, and that's expensive I suppose. Since it's a private sale I suppose it will be impossible to return the lens if it is not as described, but then I have no experience buying photo equipment used. You can never truly know what condition a lens is in unless you visit the lister and inspect the lens before handing him/her the money.
I wouldn't worry about overpaying in this case. If the lens is indeed "as new", you got it for a good price.