Diamond Comics is pretty much the only distributor for American comics in the world. If you want to go the independent route (publishing yourself) you need to get you comic submitted to the Previews catalog, they have a separate Adult Previews catalog. Once you submit it you will probably be talking to Steve Leaf or Robert Randle. Here is some contact info
http://vendor.diamondcomics.com/publ...s=254&ai=36165
Hit me up if you have any questions about the red tape at Diamond. I worked there a few years ago as a CS Rep then a Brand Manager.