Fifty euros off the Apple MSRP is "extremely overpriced"? They're the ones ripping you off for RAM upgrades, not Apple, and given that buying from Apple is a pretty simple affair, talking about the RAM upgrade as costing you more than 100 euros is disingenuous.
As mentioned by motrek I am obviously talking about the 13" model.
And 850,- is a very good deal.
Here is the link:
http://www.saturn.de/mcs/product/APPLE-MacBook-Air-13.3-Zoll,48352,325521,1271390.html?langId=-3
(It's actually 850,- in store)
The model with 8gb is 1150,-.
Here is the link:
http://www.saturn.de/mcs/product/APPLE-MacBook-Air-13.3-Zoll,48352,325521,1716364.html?langId=-3
In the regular

store the 4gb version is 1000,- and the 8gb 1100,-
In the

edu store you get 12% off, that makes 880,- for the 4gb and 968,- for the 8gb version.
So if you are eligable for the edu discount, the 8gb version is about 120€ more.
If not, the price difference is 250€.
If you are eligable for the edu discount, the price is not too bad, but it's no fun for everyone else.
Also the saturn store let's you buy on credit interest free for 33months!!
In either case, that is a hefty price for such a small upgrade.
And with interest free payments for almost three years, the mba for 850,- is a killer deal!