I have not sold any soap but I have given lots away as gifts. I have found that wrapping the bar in freezer paper works well. I print off custom labels from my computer and stick them on the bars wrapped package style (plasticy side in and just secured with a bit of raffia/string/ribbon) works...
I am really interested in this too. I would love to find a cold process recipe with 30% lanolin for my wool. This soap is just fabulous for dry cracking hands too. I am tired of paying $5-6 a bar for something I could make myself.