1

Cheapest way is to walk. After that there's cycling.

Alternatively you can try car sharing - refer to http://www.mitfahrzentrale.de and http://http://www.mitfahrgelegenheit.de/ although it might be easier to get to Stuttgart first, then start looking for a ride to Berlin. Konstanz is small.

Then you have the option of taking a train - http://www.bahn.co.uk . German trains have various offers, and a great one is called Quer-Durchs-Land ticket. This entitles you to all local trains throughout Germany from 9am in the morning until 3am the next day. If you couple that up with the travel search engine on their site, making sure to click "local transport only" - cos this pass is not valid on IC, EC, or ICE trains - it turns out you can take the

09:22 from platform 2a to Radolfzell arrive 09:45
Change for
10:06 from platform 5 to Ulm arrive 11:53
Change for
12:31 from platform 28 to Donauwoerth arrive 1327
Change for
13:58 from platform 3 to Nuernberg arrive 15:20
Change for
16:42 from platform 20 to Gossnitz arrive 19:39
Change for
19:45 from platform 4 to Leipzig arrive 20:55
Change for
21:07 from platform 12 to Falkenberg(Elster) arrive 22:02
Change for
22:12 from platform 2 to Berlin, arriving 23:48.

Total cost, 42 euros. Nobody (including car sharing) is gonna beat that. Buying a normal ticket that entitles you to use the higher speed trains will get you there in 9 hours, but it's 99 euros.

2

Or by plane - ferry to Lindau, train or bus to Memmingen and http://flug.idealo.de/ergebnis/1ted/

3

Shorter and cheaper: Ferry to Meersburg, bus to Freidrichshafen and http://flug.idealo.de/ergebnis/1tkQ/

4

30./31. October - or?

DB timetable
Start: Konstanz
Destination: Berlin Hbf

There is a connection incl. night train from Basel Bad Bf to Berlin. Konstanz dep 19:22 Berlin arr 07:19. If you buy the ticket for this now you can get this trip for EUR 69 seated or for EUR 79 in a 6-berth couchette.