Finding Purples....
I think the real true purples end up looking kinda DARK on the bolt.. its the medium and lighter purples that seem to show up on the shelves. When you put some blue with the purple it maybe shelved with the *purple blues* shelf, and when you put pink with it, it gets shelved with the fuchsia-purples and lavendar purples... i.e. when does it stop being blue and become purple ? or when does it stop being *off pink and become purple* ? Try looking in those overlapping areas, pull the nearest purple bolts off the shelf and take and put someplace else to compare, they get *more purple* sometimes depending on what they are next to.
Some newer fabrics are kept together for a while with a new *moda line* for instance... look at the shelves with newer lines, see if that line included something with a purple background and some coordinates colors that could be *purple* on that shelf.
If you do this, move the purple-blue bolts and purple-pink bolts, and *new lines that include purple* you may double or triple what you think that store has....