to my knowledge-no one sell copepod nauplii per say.
You have to raise adult copepods and their babies ~copepod nauplii are the result.
do a search for copepod culture- specifically the type of copepods used for pygmy angels(frank baenschs article), as there are a number of species available for culture w some being more successful than others for ease of culture as well as nutritional value, or read the microfood thread stickied at the top of this forum. Its a start for home copepod culture