Thanks everyone!
When I searched for other people on etsy who printed on leather, one person tagged their item with "screen print". The only thing is, from my limited knowledge of screenprinting, aren't you restricted to only a few colours? The people who are doing it on etsy seem to have quite the colour array on theirs.
I found this tutorial initially - but when I tried it the print scratched, crackled and rubbed off.. http://justsomething...ing-techinques/
I tried the dark transfers like they suggested, but that didn't look good at all, so I tried the light - which looked good, but didn't stay.
I don't think all the people on etsy doing this have access to printers that cost $15k or complex screenprinting setups, most people on etsy are crafters (like me) who DIY from home.
If anyone has any other suggestions please let me know. I read somewhere that there's a technique called "sublimation" that may work - but no idea what it is or how to do it.
OK, more hunting, found this tutorial: http://www.lilblueboo.com/2011/10/glittery-leather-cuff-w-transfer-a-tutorial-and-download.html
Might be the next thing I try since it looks closer to what they're doing.