I started buying ink as a dark neutral a few years ago and steadily accumulated more and more pieces as they came along. For me, it was just a case of being patient and keeping an eye open for the good stuff.
When it first appeared it was really only the premium brands who were doing it, so I began with a pair of tailored pants from Acne and a mini macintosh from Philip Lim (this was before he got really expensive, so a very happy score there). Both pieces are still with me and in regular circulation. It's filtered down since then and now it's much easier to buy. Now I have loads of it, including four coats. I love it.
As everyone up there says, it's interchangeable and very wearable with black and it works well with all shades of white and many brights. I also wear it with cognac and/or taupe accessories to soften it up a bit. And I prefer the ink-out effect to all black, which can fall rather flat on me.
All that said, I'm steadily working my way back to black right now. I'm using the same strategy as I used with ink - just being patient and waiting for the right things to come along. I'm enjoying it very much with bright accents and icy pastels at the moment.