Get a Behringer Neutron and a Korg SQ 1 to play with. Don't start with Eurorack unless you have a LOT of money. Gambling money to burn for an expensive hobby. 5 K at least. Will soon be 10 and you will have a wishlist for another 10 K.
A "small" case for a certain purpose will still cost 4-5 K and you would have to exactly know what you want and why. (Which i would slowly be able to do after having tried out about 100 modules and seen what i like and what not so much, not easy to do for a beginner.)
Or Get a 1010 music Blackbox (used for 400) and a field recorder and some free sample packs.
That makes a lot of sense for ambient/movie/performance soundscapes.