Here's a page on which you can post up items you want to find in charity shops.
For instance, two weeks ago I posted up (it's there, in the blog) that I wanted to find a maroon top, coat or jacket. I found one that very afternoon, 100% new wool. It turned out to be called Cherry Red but was exactly the hue I was looking for.
This works very well. Use your visualisation skills. Or if you don't know about these, try visualising something you would like to find. It may be a present, an essential item (see the expresso maker) a vintage piece of clothing or a first edition book by your favourite author. Give it a try.