I'm getting more and more refined in my system of new vs. used.
I buy new, high quality shoes for me, and I rotate them. This year, my mom gave me $ for shoes for my birthday, so I bought Danskos, and I know I'll use them for years to come. I also buy new bras, but I've never bought expensive ones. I'm about to splurge and buy a new, nicer nursing bra because I've been nursing for 2 years straight now and my bras are getting gross and ripped. I want something that won't fall apart. For other clothes, I mostly buy sale or clearance stuff from Gap or Old Navy. I must sound really elitist, but I'm not. I just wear very few different clothing items, and I hate having them fall apart, so I buy them new and take really good care of them.
For DH, I buy new shoes, but cheap ones. He's tough on shoes and doesn't take better care of the more expensive ones. I buy new clothes for my DH because I haven't found very good secondhand slacks or collared shirts that aren't older than my grandparents. DH has to wear slacks and nice shirts to work, so I buy them on clearance and take care of them. For "home" clothes, he wears jeans and mostly free tee shirts he's gotten from computer events. We also make him a "dad" shirt every year with my kids' handprints on it, so some of his shirts are purchased new and handprinted.
For my DS (2), I buy new shoes unless they're for an occasion like a fancy shoe. I buy used crib shoes like Robeez for my daughter (8 months) because it doesn't bother me to know another baby has been in them and not walked. I buy about 50% of my kids' clothes at secondhand kids' clothing stores. I sell back most of the clothes they outgrow, so I have a lot of credit there. That lets me buy filler pieces that haven't been handed down to us from there without spending $$. The other 50% of the clothes are handed down to us.