I wouldn't wait on buying clothes that fit. It's a huge motivator to wear clothing that is form-fitting as you lose, instead of wafting around in your way-too-big tents! I couldn't afford new clothes every few sizes, so I started doing the thrift stores. I pay just a few bucks for a pair of pants, and when they get too big I don't feel bad about giving them up.
I'm not to my goal yet, but I really enjoy all the compliments I get.
I have never been a skirt-wearer (at least not since I was considerably smaller), but three times this summer I've worn skirts for family reunions and parties.
I look forward to having lost enough weight to be able to start a running program.