Actually, you can import Poser Runtimes into Daz Studio 3, including your own meshes. This is probably true of Daz Studio 4 as well. I've used Daz Studio (combined with Poser and including Daz rigging plugins) to build original figures. Building original content is a bit more complicated than learning how to load Poser Runtimes in Daz Studio.

Download my free stuff here: http://www.renderosity.com/homepage.php?page=2&userid=323368