I looking for one of them,one still good and ones cracked, but I can take two

You can buy them individually from Stainless, but I suspect you're looking for used.

I don't know how old these are on my boat or if there used on salt water , I am going to take a set and change them

Buy new! From Stainless marine.

We have good prices on Stainless Marine! http://www.diamondperformanceparts.com/home.php?cat=272

You can find great deals at the powerboat swap shop on Facebook. I've seen all different types and conditions just know how to pick em and pay with paypal so you have buyer protection in case you deal with a "not so honest" seller.