To Take or Not to Take?

This weekend I am going to Frankfurt to attend the first holy communion celebration of the son of two good friends of mine.Luggage
As it is a weekend trip and 99% of the people are German speakers, I am not sure if I should carry some copies of my book there for potentials buyers.
My friends bought the very first copy of my book from Germany. I would not expect them to buy an extra copy.
Anyway, I am going to take one copy of the book and a few promotional postcards with me just in case.
I need to be ready at all times :>