It helps to not be overly picky, and to do your homework by playing as many cymbals as you can locally so you have a rough idea of what a given brand, model, or weight sounds like. The Cymbals Only web site has a lot of good sound files. And there are a ton of mostly-horrible videos on YouTube of people playing their cymbals, which are better than nothing, I guess. You can't go too wrong if you stick to purchasing pro-line thin/medium-thin crashes and light/medium/medium-heavyish rides by Zildjian, Sabian, or Paiste. And if you're buying hand hammered cymbals, add Meinl or Bosphorus— I've never heard really bad cymbals from them. Be careful about buying Istanbuls without playing them.