I feel your pain. Only I didn't want to send my old pals away, and resisted buying a bench polisher which seemed to me to be overkill, considering the problem.
FWIW, here's my current remedy--
I bought two grades of steel wool, fine and middlin. I used these on my oxidized vulcanite stems. Then I polished the stems up with a rough cotton towel. Finally, I took a bottle of mineral oil from the medicine cabinet, dipped a fingertip in in it, and spread it evenly over the pipe stem. Let sit over night. Wipe off excess. You may end up with a matte black finish. But that's better than snot green, and you don't have to send your pipes anywhere. And it's cheap. Personally,I like the "burnished through use" look more than the brand new look. And there's a bonus --mineral oil will help prevent oxidation of your knife blades.