There was a large amt of dye transfer matrix film for sale just a couple weeks ago in Germany. Fresh
batches seem to be run every few years until ... ? It is being custom coated and is not dependent upon
Kodak as a sole supplier. It never was. I know where you can get dyes. You can produce and mordant your own printing paper. Registration gear comes up for sale every few months it seems, or if you have machine-shop skills you can make your own. I know how to make color separations and masks using films currently on the market. The prime ingredient, time (lots of time) is what is hard to come by.
RA4 printing per se if very easy, but doing high-quality advanced work is just like anything else - you
need to gradually learn the ropes. I'm one of the few people attempting advanced masking operations
with it. But it is the future (at least at this moment in the future!), if you like darkroom work per se.