Wondering if there is such a thing as pewter or nickel kitchen sink and where could I get one?

I can't think of ever seeing one. Stainless, and enamel would be the most common materials. Copper is around. Pewter would be too soft. Did you try Google?

I think they make nickel strainer baskets. Most stainless has nickel in it, and it can be quite hard to tell them apart.

Nickel is likely to turn green or cause some of your dishes or flatware to. If you like green copper might be easier to fing with the same effect. I think pewter actually contains lead so not so good but you could get a look alike product in a different metal alloy or just get a stainless steel one in a dull finish. I used to see something called soapstone which might suit you but it's more expensive.

I have a stainless sink with a brushed nickel finish, hope that helps.(got it from home depot.