Wippermann and some other (SRAM?) make nickel plated chains which are more rust resistant than plain steel but, even stainless steel chains will rust if exposed to enough water long enough.

I didn't realize that Ti chains were still around. They would indeed be rustproof but the last time I saw them advertised the price was $400. And, yes, that's $400 EACH.

Best low cost rust preventative? A dry rag.