Samsung Galaxy SIII Unlocked Mini: $279 via Ebay Free shipping, $49/month unlimited
Shipping is free.
Check airportal.de to see user reports of 3G/4G coverage in your area on the 3G/4G bands this phone uses. If you are around WiFi all day it won’t matter much.
The network rollover to these frequencies will be complete by the end of the year, so it’s not much of a factor for long.
Get one and then sign up for service by clicking Enroll under my picture.