Echoing start slow. I didn’t start slow - I caught the bug hard, and unfortunately had the ability to fund the habit (not intending to humble brag, just explaining). I’ve ended up with much more than I need, which makes it hard to learn things deeply, and also a number of modules I’m trying to pass on in a softer Eurorack second hand market.
All this is to say, go crazy if you want, but you will likely not stop at 104hp if you allow yourself to build up to it quickly
For the 0 Coast specifically, I think it depends on your other gear. 0 Coast almost expects MIDI, and some of the functionality of it can’t be accessed without it (the arpeggiator mostly). I’m pretty sure you could send it MIDI from your Elektron gear, and arpeggiators beg to played with piano keys IMO, so if you have some keyboard in your life that can send MIDI to it that would be great. Bonus is that 0 Coast can function as a second MIDI-to-CV converter, so you can get two sequences out of your MIDI gear without anything additional. You can of course sequence the 0 Coast directly from CV sequencers, but unless you don’t have MIDI gear in the mix, that feels like it’s just using up a sequence voice.
As cliche as it is, Maths is still an excellent first/early module. It provides you with a lot of functionality you will always need.
The Disting Mk4 is a great early modular choice because it does so many things. It also allows you to explore different categories at low expense, and it will probably continue to be useful long into your modular journey. And, it is in demand, and will sell easily if you decide to let it go.
o_C was also one of my early modules, and I think it’s a great early module. Just be aware that o_C really needs triggers to be useful, so you need some sort of set of gate-sources. To some degree O Coast can provide these for itself, but you might consider looking at something like Tempi or Pamela’s New Workout. Batumi can also fill this role some.
Plaits is also a great versatile first voice, and can be driven as said via MIDI through 0 Coast, at least to start.
Go slow it’s exciting, but it can get out of hand quickly.