I am a novice but I know I am limited by my current d5100 and I want more manual controls. I have 3 standard nikkor lenses including the dx 35/1.8, dx 18-105, fx 70-300.
I have seen and read about the d7100 and d7200 and I like the weather-sealing but I don't like that it is missing a swivel display like my 5100. The d750 has some swivel but would have to be an import because the US version is $2000. So which Nikon body should I get that will give me the best learning experience or should I sell everything and get something else (mirrorless, another brand, etc)?
Max budget is $2000 and choice includes:
1) New Nikon body plus one (1) used quality glass for astronomy telescope (wife loves watching programs about space so it will be an easier sell

)
2) Completely new setup (different brand, mirrorless, etc)
Thanks