James,
Pretty sure original was zinc plated, with nipples nickle plated. I had two sets zinc plated and it was around $50 for the spokes, nipples were dearer about $100 I think. Cad plating is not available much now, too toxic for the plating people I think?
Note mine have been on the bike for 5 years now, and I have covered 10,000 miles, and have been in rain etc. The front spokes are tarnished now, not rusty but dull finish so they won't last forever if you ride the bike. Chrome is to be avoided, due to hydrogen embrittlement, but otherwise a dull chrome finish would be great!
Cheers Richard