There was a time when we had silver waterblocks. I know Little River had a silver Storm G5 available. IIRC was $200USD back in 2005.That is one heavy monster.
I do want one of these companies one day to make one out of Silver (unless that's already happened and I've missed it) just because.
I thought someone had released a special edition silver heatsink at some point, but google is failing me. So maybe not.