I am also a merchant and unless I am including a small light set with my textures, I always render my promos in the Poser Pro default lighting. Unflattering, maybe, but it shows the character texture in its default state, and shows the customer exactly what he is getting. Maybe thats why I don't sell a lot of them, lol.

Some people dream of worthy accomplishments,
While others stay awake and do them.

I am a dreamer