I have considered doing this, but have never taken the plunge. If I were to order today, I would probably get the garment designer (I think that's the name) by cochenille, available at www.cochenille.com.
I have also looked at patternmaker but it didn't look flexible enough to me, there is a freeware version that you could test drive, haven't done that either. I think the website is www.patternmaker.com.
There are some others available, but I can't remember the names. They are all so pricey. I would really like to hear from someone who has used them before going there myself!
Very little actual information to offer here, sorry,
but maybe that can help start your search. Would love to hear more myself.