There are ethical issues with any animal product, and I think everyone has to decide for themselves what they are comfortable with - I know how you feel, I'm not quite sure where I stand either.
But there are legal issues with animals that are now endangered species, such as seals. As far as I understand it, trade in endangered animals skins is subject to different regulations in different countries. Some products simply cannot be sold at all, some can only be sold within country or state lines, some need certification of some kind. It depends where you are, and where you are selling to, and what the item is, and in some cases how old it is.
You might want to look up CITES (Convention on International Trade in Endangered Species), as well as your own country's regulations.