I used to sell wild type livebearers, usually about 30 boxes per shipping season. After a couple of years, I sat down and calculated shipping supplies and mailing costs versus profits. The post office made a lot more money from my 'business' than I did. When you are small volume, advertising and selling may not be a good idea. You need a thick skin.
Shipping to friends always is a good plan, but on the open market, you know that if the post office messes up, you'll be treated as if you own the system, and it'll be your fault.
If you have extras on the Tateurndina you breed, a local store is a way better option.