I would suggest that you look at the price again. The keyboard will be the least of your troubles.
US prices are always quoted without tax and delivery. This alone will make a big difference.
You also get no one year warranty like you get in Europe, Apple Care costs extra. Also, you cannot purchase Apple Care in the US that is valid for Europe, meaning should your PB ever need repairing you are buggered.
If you do decide to go ahead and buy your PB in the US make sure to mail the documentation home. If you're unlucky and get stopped at the border you won't have to pay import duties that way.
Apple equipment costs pretty much the same the world over nowadays if you take local taxes and charges into account.