It was an limited-run earlier product...several years back, from around when the reissue came out, and it wasn't cheap, something like $1000 compared to $449 for the MS-20 Mini new and maybe about $400 or less used. At the same time, though, the keyboard version is still very much worth having, plus there's no jack conversion needed (the original '20 as well as the kit module used 1/4" jacks). It's not as large as the full-size version (I've had both at this point), so it's a bit handier, plus the keyboard also has a mod wheel and momentary button switch for various uses with their own patchpoints, which can actually be linked up to something other than the '20.
But, yes...sample-loops made with this can be made to sound like some sort of circuit-damage nightmare when you feed that input section with the right (ie: 'wrong') things. Another nice thing is that its matching SQ-1 sequencer is set up for the Hz/V scaling already and that its sync should lock up nicely with the Volcas. Not only that, it outputs MIDI and MIDI over USB (yeah...it can sequence software synths, too), plus has a special port for those littleBits modules, and it's built like a tank. Damn nice for $99! And yes, it'll also talk just fine to the 0-Coast...and can do that and talk to the MS-20 Mini with the right scaling at the same time (albeit with only 8 steps each...can't chain row A and B when doing that trick). I really think that it and the Arturia BSP are perhaps some of the finest affordable sequencing hardware...perhaps EVER.
Additional mixers: eBay. You can actually get really amazing steals on higher-end PA mixers from several years back for dimes on the dollar. Just a cursory glance shows several small-format units that originally came in at $1200 or more selling for about $300 and less at present. If this sounds like an idea, there's several things to make sure of, but most notable is that you do not want a mixer with onboard effects. This is because you don't necessarily find the best effects units in these in terms of tweakability, and you want total control over your AUX bus architecture instead of being locked into a manufacturer's idea of what you should be doing. PM me at some point on here and we can discuss this, since it's a bit outside the 'synth' topic zone.