I'd pick up a second Z3000. They FM incredibly well together.
-- TriangleMan

I thought buying a second VCO but mostly because I have the opportunity to get an AS RS95e for 80 €. But yes..a second Z3000, why not, I really like it!
Correct me if I'm wrong: for a basic full synth voice, I just need to grab an LFO. But if I want to make rich and complex ambient or industrial textures and process some external sounds, I need a lot of modulators! So wtb next: pay the price for an all-in-one module like Math (enven if the complexity scares me a bit) or take some entry level LFOs/RM/S&H/Noise modules from Doepfer..?