i buy designer stuff as often as possible... obviously depending on my finantial situation - which is not always good
-... but once you start buying designer clothing and accesories anything else from "ordinary" stores starts looking uninteresting for some reason... i usually go for expensive cool designer stuff or ridiculously cheap stuff from flea markets & weird bargains u can eventually happen to find when you less expect it.
of course i also own stuff by rather cute italian brands such as Miss Sixty, Killah Babe, Fornarina and such (good quality stuff even if not from reputated billionaire designers) but i got sick of clothes from stores like Zara, for instance. they only sell bad rip offs of designers' stuff and the quality is very bad plus everybody wears that stuff (at least where i live) and that makes girls over here look the same... really depressing...
as for the designing stuff, I own clothes from D&G, Armani, Versace, Marc Jacobs, Dior, Cavalli, Anna Sui, Sonia Rykiel, Prada, Chanel, among others, as well as accesories by Miu Miu, Gucci, Tiffany and Co., Dior.... i bought some of those items on sales and some others were gifts and of course not all of these items are from their main lines, some of those items are from the designers' young lines which are expensive but not absolutely unaffordable. But i am of the opinion that the way you combine things and attitude is essential when it comes to dressing cool. sometimes the clothes do not make the girl!