Well, you could build up an entire system out of "primitives", ie: the very basic, mostly single-function modules. This would be as opposed to the "everything in xx hp" approach of the combined type modules. But doing so in Eurorack = Eurorack prices.
My main modular, though, is pretty much ALL "primitives"...an AE system, 180 spaces. And how much does it cost once it's fully-populated? Hmmm...maybe $6k...$7k if you really push it and include the Tektronix lab-grade linear DC supply I use with it. But the neat part is that it then becomes easy to build simulacra of typical complex modules. For example, this has either six complex VCOs when you use the colocated VCAs and mixer (it's sort of like a four oscillator variation on the usual two oscillator architecture) ...or you can just treat those configurations like 24 VCOs, 12 VCAs, and six mixers in other patches. And if you're into prototyping, they even have their "BrAEdboard" module, which puts a proto board right into the modular itself.
The main drawback is that, like Lunetta circuits, etc, these things only work with a 0 - +5V range. But while it might seem like that's a serious problem when it comes to external device interfacing, all you need is one of Soundmachines' Nanobridge boards and you've got incoming CVs and gates/triggers constrained to the proper voltage range. And audio can enter the system via an AE four-channel dedicated I/O module. Plus, you have to work with pinwires instead of the usual sorts of cables...but tbh, this has to have been one of the least-regretted things I've put money into. And while I know Eurorack pretty well and I've got some Eurorack gear here, when I need to do some seriously deep patching, I fire up that Monster From Murnau.