That is due to the availability of ARM from Atmel in germany. German stores don't offer them (as far as I know) and so I decided to start with the UC3B which is available here. The STM32-F1-series is also available here, which looks interesiting to me too. It would come at lower price for controllers and programmer (Dragon / ICE vs. ST Link V2), but has a huge downside with it's not existing IDE. I've already lying a NUCLEO on my desk. Actually I'm very happy with Atmel and it's visual studio clone and depending on my experience with the AVR32 I would consider buying the ARMs from digikey.com in the future. As a hobbyist I have to consider the shipping fees, when ordering chips from digikey, farnell or mouser or have to purchase beyond some limit to get free shipping. But you're right, these SAMD look very nice