The best D|S advice I can give you is to take some of that money you plan on investing on new models and invest it in D|S plugins. Judging from the image you attached you might want to look into pwSurface(DAZ). Also poke throught the DAZ forums for the various free shaders like pendragon's excellent set which comes with an IBL capable environment light.

Rather than bolstering your model count look into these D|S empowering products...

pwSurface
Light Dome Pro
Studio Light Pro
Mood Master
Uberspot Light
Uberpoint Light

D|S might be free but is capable of awesome results if you boost it up some. On a similiar note Poser and Carrara won't magically make anyones renders better. Gotta know the basics and D|S is a great place to start. Post some art too, critiques help.