I don't shop for 2nd hand clothes much but...

There are some department stores that have quality stuff but it is typically overpriced. Way, way overpriced. However, such stores usually have several sales a year. One I go to has 65% off plus an additional 50% off sales at least twice a year on stuff they are clearing out. This tends to make way overpriced stuff quite reasonable.

I'm not much into expressing myself through fashion (barring the occasional t-shirt) so as long as its comfortable, relatively inexpensive, doesn't scream "Oh my god, I'm hideous!" to me and is of decent quality then I'm happy.

I don't think I care enough to spend time designing my own stuff but you are right about it being much more accessible these days. It's something that should definitely appeal to some people and there seems to be a lot of custom and semi-custom stuff out there these days.