I second re-galvanising. I got it done this year and the anchor looks like new. Some places are not good with chain though. Ask if they have a vibrating rig for it. And see if you can bypass that minimum order charge by trying to merge your lot with someone elses or a steel fabricator's. Ask around, you may be surprised how helpful folks can be.

In tha last analysis, it may be cheaper to buy new chain, but not a new anchor.