From the prebuilt synths you're describing, I think it might be possible that you're painting yourself into a corner by limiting the budget on these. The M32, small Phattys, original Minibrute...all of these are pretty limited solely by the fact that they're inexpensive and therefore don't contain the complexity of higher-end prebuilts. But when you start getting into the more complex monosynths, or going away from the analog (which is another 'too trendy for its own good' thing) end of synths to explore good digital synths, you get back into the sort of sonic complexity I think you're aiming toward.
Again...back up and do some research. The solution to doing things over long-term is to never act quickly, but consider where you want to go in the long-term. And this takes time. Hell, you might find you can get sounds out of an old Casio CZ-101 that are just what you've been thinking of, but without a lot of research into where you should go with your musical ideas, you'll never figure an intuitive leap like that out.