I buy fabrics via computer it is sometimes difficult but I have found that colour distortion is the same on all pics so they all have same shade. Buying from sales I purchase enough for a backing then it doesn't matter. I also have a terrible memory and sometimes forget which pattern a selection of fabrics for,hehehe , and they have to goin my stash.
I frequently buy fabric from USA and I purchase specific fabric ie words ,phases, specific pictures pens, wine bottles, monkey, insects etc. these fabric not always available in UK also they are cheaper although many of my parcels are ripped open at customs and then charged extra and not put together again. I don't think I have ever purchased a Colette set of fabric deliberately for one project. Even if I did I would have altered the combo I always do.