Hi!
Thank you very much for this quick and informative answer! I will buy the N40 magnets!
I would like to buy them here:
http://www.neodymium.de/
Click on "Quader groß" on the left navigation bar! The N52 version would cost around 1,30 Euro more than the N40 version (I think that might be around one US Dollar difference if I can remember the cange rate correctly)!
Best,
Heiko
P.S. I looked the change rate up ... one N52 magnet would cost 20,80 US $ and one N40 would cost 19,16 US $ ... 25% discount if you order more than 10 magnets! :-)