I'm sure Phil C will not be upset at my saying that the only way to make really top quality clothing is to model it from scratch in a modelling program.
  Having said that, the clothing designer bundle offers a very good shortcut for those of us who lack the skill and/or time to create from scratch. Even for clothing made in another application I tend to use the obj-to-Cr2 converter to make conforming clothing - that is a real time saver!  So I would say that although not a must-have, I certainly do not regret buying the bundle.

An alternative starting point would be to try something like the (free) morphography quick suits for M3 and V3. You can import the meshes into a modelling program to complete them, and you would probably find a UV mapping program (UV mapper, either the free "classic" version or the pay-for pro version) useful. Again this approach will not instantly produce top quality clothing, but will give you a starting point.

Making Poser clothing is neither easy nor straight-forward, so be prepared for frequent set-backs and frustrations.  Good luck!

"Don't make me angry. You wouldn't like me when I'm angry!"