* Mondo could be the app, but correct me if I'm wrong, but it's not as easy to play with as it would be as Poser and a Daz figure with the built-in morphs. Sure, you can always sculpt and do your own, but if you are talking about the HUGE mass market appeal of selling like here at Renderosity, then look no further than the market place. Almost 90% of all new content is for the current Daz figures. So, unless you have a design team behind you, I don't see a way to possibly make enough cloths, props, etc. to support any figure for mass market. 

Yep!  I suppose the Daz figures have a certain comfort zone.

*Also, how and could you add hundreds of morphs to your custom figure in Modo to make it easy to sculpt for body, face and expressions like the V4, M3 figures by Daz? I don't know anything about Modo other than Daz V4 was created in it. That's why I was wondering how hard it would be to do all those morphs for a figure you design yourself. 

Not hard at all.  Study anatomy then take a few live drawing classes,  a few sculpting classes. 
Study expressions and body language along with motion and gestures.  Apply the knowledge you've learned as you push and pull vertices,  edges and polys.

*Again, I think we are comparing 2 different ways of doing things to 2 different markets. One is more professional and taking a longer time to learn and work with to achieve what you want. The other is giving you ready-to-go type figures and software. I see the advantages and disadvantages to both sides here. 

I agree.  There's only one difference between Daz  figures and Renderosity figures.
We made the developement of our figures public and we listen to what the public wants from our figures. 

I have a question.  Which figure would you like, one off the rack or one custom made?