Some suggestions of how to get there

Coming from Barcelona :
Ryanair planes from Girona to Karlsruhe.
Then from Karlsruhe you'll have to take the bus 205 (to Baden-Baden train station) + train (to Sinsheim) ; following the below link you can see aiport website and found all bus time table ; choose your language and then click on "Bus companies":
http://www.badenairpark.de/
And here below, the link for trains :
http://www.bahn.de/i/view/USA/en/index.shtml

You can also choose to rent a car! Maybe easier and cheaper at the end....

Planes from Barcelona to Stuttgart :


Coming from Paris :
Take the trains from Paris de l'Est direct to Mannheim (3h and cheap!) then from Mannheim to Sinsheim by train (20 min)
By car : 570km / 5h10

Coming from Lille :
Take the train from Lille to Paris , then Paris-Mannheim, and then Mannheim-Sinsheim
By car : 580 km / 5h15

Coming from Mannheim or other places in Germany... you should know!! :-)

Coming from Faro :
Andreas & Ricarda : take the plane from Faro to Memmingen, then the bus or taxi to the train station ; and then the train to Sinsheim