Since I'm also based in Germany, may I ask how you do marketing, where you get your gigs? Agencies, word of mouth, previous employment?

What technologies do you do, do you cover the whole tech spectrum in that area, how many years experience, are you in Bavaria (where rates are a bit higher than elsewhere)?

Most advertised job offers seem to be only through agencies, and over here hardly any freelancers work without agencies. Plus 100€/hr is pretty high (for a non-company rate), so you must be doing something right.