QUOTE (blue78 @ Nov 20 2007, 12:37 pm)

As of 1 January 2008 all vehicles must have a Green Emissions sticker to drive within the limits of the City of Berlin. If you are stopped by the polizei after this date without one, you will be fined.. (30-40 Euro's) for first offense.
But i heard they can be purchased almost anywhere
The Umweltzone boundary is actually the inner S Bahnring not the city of Berlin limits. The fine for crossing the inner S Bahnring will be 40 Euros and a point on your license at Flensburg. From the first of January 2008 you will need either a green or a yellow sticker to legally cross this boundary. Only from the first of January 2010 will you need a green sticker.
There is a
General information section on the Berlin website with a link to an English pdf explaining everything in detail.
Most, if not all, garages are selling the stickers. They do, however, seem to vary in price. You can consider yourself to have a good deal if the sticker only cost 5 Euros. Obviously not if you spend a further couple of Euros on petrol to get there.