I'm never ever gonna pre-order a steelbook @ amazon.de again if the price is above 20€.
Just add it to your wishlist and check once in a while (if possible, each day) if its price is below a certain level. If so: Buy! Should work almost anytime.
It's sad to see that most of my Steelies are now on sale for about 9,97€. I could have saved a lot of money if I would have waited till now...
e: Some months ago I realized that f.e. Shooter, Hancock and War of the Worlds were not available anymore. About two weeks ago they were in stock again for about 14/15 €, I ordered them for sure. Some days later the prices got even lower. So, even if a title is out of stock for quite a while, there's still a good posibility that it will be sold again in the future, probably for half the price.
ee: I was angry about Warner Europe for a long time, because they're printing the FSK-Stickers onto their steelies 'n ****. But in fact, when I look back, they're doing it right. At least I got some kind of an "exclusive feature" if I pre-order a Warner title, as its re-release gets a crappy print-on that I do not have on my steelie.. whatever, sad story.