Barry, they work well on open porous surfaces like slate or ceramic. Not a big fan of them on anything else, some guys like them on metallic, but I have not had the best of luck with them with these surfaces. They sound best to me on the slate, but the key to a good ivory striker is the direction of the grain in the ivory, yep it has grain, I like the straight vertical grain in mine, keeping it clean is essential use alcohol wipes for that. Cost? Depends on what you want to pay ... mine are 15.00 each, I have seen them as high as 35.00 each and higher depending on the maker.....
