I've been a musician for a while now - up until quite recently my weapon of choice was a bass guitar, but having fallen down the rabbit hole that is modular synthesis I have a new way to make noise ...
I started out the usual way: buy a rack and a bunch of modules (ADSR, VCA, VCO, that kind of thing) and start making noises. Then I discovered the DIY scene and it all snowballed from there - sequencers, filters, logic modules ... four racks full of noisemakers later and I'm still not done.
My modules are Eurorack-friendly by default (3U high) - although I have 'proper' PCBs made for them, all of the soldering and testing is done by hand ... that includes all the surface-mount stuff in the newer modules. I'm a big believer in the KISS principle - Keep It Simple, Stupid! If you want all-singing, all-dancing multifunction modules then this really isn't the place for you - similarly, if you're after ultra high fidelity then you may well be in the wrong place; I like my sounds to be lo-fi, dirty and more than a little bit strange.
Finally, yes, my modules are pretty cheap - the reasons for this are simple: I sell this stuff to supplement my existing income and to fund a hobby I enjoy - board runs are kept small (usually 10 at most) and I try to keep costs down where practical; this was one of the drivers behind switching to surface mount - that, and I enjoy the challenge of soldering SMD. For the really curious, despite working as a software developer I do have a PhD in theoretical physics, specifically the numerical simulation of explosions. It isn't nearly as interesting as you might imagine :-p Now, go forth and make an unholy racket!