What Looniper said. You don't have to buy the DAZ figures, but you'll probably want to. There's a reason why almost everyone uses them. Kind of the reason almost everyone uses Windows. It may not be the best, but it's pretty good. And the fact that everyone else uses it makes life a lot easier. If you want to become a 3D modeller, maybe you'll enjoy learning to make your own figures, morphs, clothes, textures, etc. But if you want to make art, you'll want to buy a figure with a lot of support. So you don't have to make all the clothes, poses, textures, etc., yourself.

That said, you don't have to buy the DAZ figures right away. You can stick with Posette and Judy for awhile. Maybe wait for a good sale. Judy takes V1/2 textures, and there are some very high quality textures for V1/2 out there. There aren't that many clothes for Judy, but if you use dynamic clothing, it's not too hard to fit V3's clothing to Judy.

Another thing to keep in mind: the Face Room only works for the P5 people. You won't be able to use V3 in it.