base.de currently has a weekend offer. If you sign up this weekend (as of now obviously until midnight today) you'll get 2GB for €18.75.
Effectively you´d have to add €3 fot the all-EU option.
As a summary you can have:
- 2GB, usable throughout the whole EU+CH
- all calls to Germany (no matter from where)
- at €21.75/month
Once the 2GB are up you can choose to continue unlimited surfing at reduced speed (56k), or buy additional speed packages.
They do have this offer from time to time, so no need to push it too much if you're only considering it.