If you made the character from the Poser nude man or woman, no, you could not sell the model. People sell "characters" - morphs and textures for existing figures. But they don't include the actual geometry. You can use software like RTEncoder "encode" your file so that only people who own the original mesh can use it, if for some reason the geometry must be included. People do make money selling Poser models and images, but do not expect to get rich doing it. And it's unlikely many people would be interested in buying characters for the P4 nude man or woman. These days, the DAZ generation 3 figures are where the money is. My advice is to treat this strictly as a hobby. One day, you may well make money selling your models, images, or animations, but as a newbie, it won't be any time soon. Don't buy expensive software thinking you'll make the money back by selling your art and models, because you won't. Not until you are a lot more experienced, anyway.