Dream to go to Germany

It's been my dream for a long time to travel round Germany as I study German so I would love be able to practise it in a native environment. Other than this, I met lots of wonderful people on a summer camp and many of them live in or near Germany so it would be amazing if I could see them again as it was painful saying goodbye, not knowing when we'd next meet. If I go to Germany, I would like to visit Frankfurt and Munich, and maybe Berlin or Cologne. However financial difficulties mean I will not be able to afford to travel to the country for the length of time I'd need to be able to see the country properly. I appreciate any contributions, no matter how big or small they may be. Thank you so much!