Is there a "cheap" (let's say 15/20 pounds top?) chain that doesn't rust that easy?
What sort of chain? For single speed, Wippermann 1Z1 or 7Z1. For derailleur use, not so much. KMC ZnXRB for n-speed derailleurs are only just outside your price range.
What sort of chain? For single speed, Wippermann 1Z1 or 7Z1. For derailleur use, not so much. KMC ZnXRB for n-speed derailleurs are only just outside your price range.