You don't need a lawyer unless there are factors that complicate the case like a criminal history or one or both of you having filed previous K-1 applications and even then you still might be able to go it alone.
Using a lawyer actually slows the process as you still have to gather all the papers yourself then give them to the lawyer who will file on your behalf. I found it easy to do by myself. Once you have all the paperwork you need as evidence you can fill out the forms by yourself in less that 3 hours. That's allowing for checking as you go to make sure you get it right.
Go to http://www.visajourney.com for free guides and advice on how to do it. You will find couples there from all over the world including quite a few with German fiancees who can tell you more about what your fiance will have to do in Germany.
NY will issue a license to a lawyer who is licensed in another state and has been practicing for 5 of the last 7 years. It usually takes about a year for the court to rule on such a motion.