It's not that difficult or expensive ($20), and actually can be quite rewarding. The gunshop method of stainless steel tanks and acid/blueing salts is the best method, but it is not necessary to get a decent job if you are willing to do some careful metal prep. manually. I have done several guns over the years and the worst part is preparation. Steel wool, scotch brite pads, and emery cloth remove the old bluing quite well with a lot of elbow grease, and the bare metal must be thoroughly degreased with Methyl Ethyl Ketone, Acetone, or even Alcohol, and latex gloves worn throughout the process to keep the oils in your skin from contaminating the metal after it has been degreased. Care must be taken with guns that are engraved in order to avoid removing or damaging the engraving. A blueing remover (acid) is advised for engraved guns since it is almost impossible to completely remove the blueing from the engraving. Common sense is necessary to avoid creating scratches which run perpendicular to the metal "grain" (ie. don't use lengthwise strokes on a barrel - use a twisting motion) If the metal is not prepared properly you will get a lousy blotchy job. I have used Birchwood Casey cold bluing solution with much success, but I would place the barreled action in an oven for 10 minutes at low heat (200 degrees) before applying the blueing solution. I would repeat this 3 or 4 times rinsing with water and degreasing between applications to get a rich blue/black appearance. I recently bought a new process made by Wonder Blue and plan on bluing an old Ithaca Mod.37. I have heard excellent reviews with regards to Blue Wonder. Count on spending two days to blue a rifle properly.
Sure, anyone can do it...poorly. A professional look generally takes a pro set-up, a lot of time, and a lot of experience. Oh, and $$$.
Most cold bluing solutions are sold in 2 to 4oz bottles....they are meant to be applied by hand, not dipping. Additionally, to buy enough to "dip" would cost you more than having a gunsmith do the job for you! Imperfections are not cured by "dipping", they are cured by removing oil and old finish from the metal. Any metal that is completely clean and degreased will look perfect after cold bluing - but this is easier said than done.There is a trick to doing cold blue.
To coat evenly without streaks’ or needing buy a large amount of blue to dip, get some 2 or 3 gal. Zip-lock bags & put parts in the bag with about 3 or 4 oz. of cold blue solutition. Then shake (rotating as you go) if you need it darker or want it to go faster heat the parts first. Just hot to the touch (but don't touch it with bare hands) about 150 to 180 deg. To do long barrels you can get vac-u-seal bags the type that comes on a roll, so you can cut just the right size bag. Remember to plug the ends of the barrel to keep the blue out of the inside of the barrel.