If you're interested in alodine supplies, try any good aircraft building and maintenance supply, like Aircraft Spruce (aircraftspruce.com). Look under metal prep supplies. It's really butt-simple, even an old jarhead like me can do it. Your biggest concern is proper disposal of the stuff after use. If you can find an auto parts store that does used oil disposal n such you should be GTG. It is re-usuable but depends on if you want it laying around or not.
Basically, you just dump a bit in a container, then put the part(s) down in there. Use a 1" paint brush to "paint" the alodine on, so it soaks in good and even. Shouldn't take more than 5-10 minutes. Then you do a fresh water rinse, and blow dry. The parts are now ready for your favorite coating. The beauty of this system is you don't need any expensive chemicals, heating to any certain temp, adding current, etc. to apply. So it can be done easily in a home workshop. (Just make sure and wear rubber gloves-that shit does burn!)
We did this kind of metal prep all the time when I worked in the aerospace industry. Worked well as touch-up on small parts you are drilling/riveting together. Works just fine on AR stuff as well. Not as durable as anodizing, but so what. I usually coat everything myself anyways, so no big deal. A nice coating of KG Gunkote has worked just fine for me over the years, in lieu of anodizing (which got blasted off on the first re-furb cycle). I know the purists will be cringing at this, but IMHO, a good coat of KG or Cero coat will work just a good as anodizing/Parkerizing.