I've been toying with the idea of a seller account, but am hung up on the shipping options. I see no information regarding how shipping costs are established or managed (the shipping options listed on the sign up page start pre-populated with the same values, and do not allow for editing). I'd need to be able to set my own shipping rates if I were to do this (to cover bubble mailers, top loaders, and the shipping costs). What management options are available, or where are price policies for shipping and handling discussed?

You get a new link under the left menu called "My seller account" under that you can set your own shipping options. You can only ship to your own country right now, but you can set different price levels for different quantities of cards. It's entirely up to you though what values you put in.

Thanks.