I wish I could find a lower cost ink that truly does what Iroshizuku inks do. I can find well behaved blue-blacks: R&K Salix, MB-MB(IG formula), DRI in the right pen, Sailor Sei-Boku (I prefer this to just about any blue-black, but price + maintenance issues). Indeed, I don't own Shin-Kai, because I have other blue-blacks that cover it.
But, I've had a harder time finding blues that function as well on different papers as Iroshizuku's do. Midway Blue feathers on our office paper, Blue Eel feathers, pretty much all of the "bulletproof" inks feather/bleed, Diamine Sargasso Sea is a joke on our papers and is really hard to clean out. I invite somebody to send a non-IG, non-premium, non-nano blue ink sample that works on "Universal" brand paper, or even worse, the recycled variant.
Until I find such an ink, I'm sticking with supporting the "premium" inks. You can't put a price on performance.
Hehe ... sitting here listening to the soundtrack from "Black Lagoon," an ultra-violent anime. Ending credits piece for it is interesting, reminds me of Barber's "Adagio". In honor of the anime, I should load up a pen with Diamine Matador for the blood ;-P
Imagination and memory are but one thing which for diverse reasons hath diverse names. -- T. Hobbes - Leviathan