I use to buy from http://www.ac-foto.com. They are based in Aachen, Germany and offer fairly priced stuff. For instance, a year ago I bought a brand new SB28DX for 350 euros including shipping, while the item in Frankfurt cost around 450.
They also sell used equipment. So far the best online photo shop I have found in Germany. There are loads of smaller places selling online. Check out the
The site is seachable and I found it very useful.
hope this helps