Hmmmmm.... you can do it yourself if you get a home vaccum pack thing for food. Then you need to find a good thick back long enough to do the job. With a little Google-Fu action I'm sure you could find it. Maybe you should ask at some Survival type forums, starting here.
I know if I had to go into the process blind I would wick the barrel, bust out some cosmoline, and stuff some desiccant packs in the bag before I sucked the air out. Then I would dig a hole, find a big enough I.D. PVC pipe, the glue, and two PVC caps to seal it, insert the bag, pack it all with grease, seal the tu.... oh wait, you just want to bag it right?