The bonsai scene in Frankfurt doesn't look too positive:
Hello Greg,
thank you for your mail.
I am so sorry, but you cannot find in Frankfurt and arround (50 km) Frankfurt Bonsai-shops.
We have same Gardenshops, there you can find rawmaterial.
Many Greets from Frankfurt
Heinz Peter Ulrich
Frankfurter Bonsai Freunde e.V.