Ill start with a small frame from doepfer (circa 200 Euro). You also get all the Bread&Butter modules from Doepfer at a very good pricepoint.
-- a vca & with a vc controllable Envelope generator (Doepfer A-141-2, ca. 130 euro) to be able to play the grandmother with dynamic loudness
-- for FX&Delay Id add an expert sleepers Disting mk4 (ca. 190 Euro),
-- for additional modulation maybe a make noise maths (ca. 300 Euro).
-- to connect the thing to a daw, an expert sleepers es-8 might be handy (ca. 450 Euro).
-- As a standalone sequencer & sampler Id recommend an Electron Digitakt (ca. 700 Euro),
-- add a DFAM for drumsounds (ca. 550 Euro).
-- for convenience: an extra Headphone amp: Doepfer A-139-2 (55 Euro), so you can hear stereo-FX of the Disting via Headphone, also very handy for the ES-8, as this has no Heapdphone amp.
-- to mix more devices youd need a mixer like the Doepfer A-138S (75 Euro).
I think you dont need an extra ring modulator, because the build in lfo of the grandmother is very precise an scales very good to 1V/Octave, much better than the Mother 32.
Oh yeah an I forgot: A Boss RE-20 Space Echo. Its just made for this
