Hi, newbie here !
I have a pretty good knowledge about synthesizers in general, but never played around with a modular synth before and I might have a budget soon (from 1000-2000€ max) to build one.
The goal is to make a cool « glitch machine » (seq & bass sounds + other tones and FX).
I’m looking for crazy and odd modules to break the audio signal.
I should be able to send MIDI and audio from Ableton (I have a Focusrite 18i20 with MIDI IN & OUT), aswell as building a sequence from scratch from the unit itself (tonal, including scales would be the dream).
Regarding modules, here are some that caught my attention :
Oscillator - Mutable Instruments Plaits, Noise Engineering Basimilus Iteritas Alter, Dirty Glitch VCO
FX - Qu-Bit Data Bender
Multi-FX - Erica Simps, Endorphins Ghost
Mod - Make Noise Maths
I’m not sure about what filter to choose and I’m pretty confused about all the utilities needed in my case.
A bit hesitant regarding VCAs (which one ? how many ?).
And don’t know where to look for a module that would make sure the notes/scale I’m aiming for are/is correct.
Don’t know if I’m naive regarding budget, any help would be greatly appreciated ! 
EDIT : Thank you for the detailed responses ! A sequencer/quantizer such as Pamela's Pro Workout, combined with the Basimilus Iteritas Alter, with some modulation/LFOs and a VCA seem to be a good starting point to experiment with patterns and interesting bass textures. A MIDI to CV module to add when using Ableton as a sequencer.
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