I buy fabrics for a specific purpose. I just can't manage to buy someone's random scraps quite yet. We have 80+ people in my quilt guild and probably 1/3+ of them happily shop at JAF/HL so when bags of scraps show up at guild raffles, I never bid on them because who knows where the fabric came from or if it's going to tear the moment I put it in my machine (I'm not exaggerating, I had that happen; lousy fabric!).
The quilt shop is a different story altogether. I can literally spend hours picking out the "perfect" fabrics for my quilt. I try to buy just a little extra beyond what I need since I don't have much room to store remnants. I have one under-the-bed tub for fabrics & that's it. That has to hold remnants & whatever fabrics I'm using in my current projects(s). I did see a "Fat Quarters Organizer" at JAF the other day, though. It was very hard to resist. Seems like that would get me in too much trouble.