[Alexander Peri] “footage that is almost comparable to RED/Alexa in decent light”
By “decent” light do you mean outside and primarily lit by the sun? Indoors with a typical Kino Flo package? Arri/Mole Fresnels?
[Alexander Peri] “with great space for grading etc. “
What do you mean by grading? Do you grade your own work? Where does the footage go? Is it done in Resolve? Premiere? FCPX? Are you shooting LogC with the Alexa primarily? Have you ever graded LogC footage?
[Alexander Peri] “Black Magic Ursa Mini 4k “
I would absolutely not consider this camera in your position.
[Alexander Peri] “GH4 with cage, Atomos monitor,”
Scrap the cage, and the use of the Atomos is rather dependent on what your description of your grading process is.
[Alexander Peri] “Black magic micro cinema camera with black magic external recorder, cage, mic, tripod and steadicam + 2 lenses. (fits in budget)”
This would be okay, scrap the Steadicam idea. Learn to walk before you start to flight. Forget the cage. What kind of mics are you considering? Shotgun? Lav? Wired? Wireless? What is your typical use of mics in your experience on set? Walk and talk? Sit down talking head?