Tom
Don't be intimidated by rust bluing.
It's an easy process to learn.
A bottle of bluing solution will do dozens of barrels and there should be plenty of info on-line to walk you through it.
The only equipment needed that would be specialized is a tank long enough to boil the barrels.
Steam will convert rust as well as boiling so one of the small Chinese home steam cleaners might be worth investigating as an alternative.