I am a bargin shopper. I don't like to pay full price unless it is a super special fabric or I absolutely NEED it to complete a project. My Joanne's fabric in town just moved locations, so they liquidated the old store, I got tons of fabs at 50-90% off the already sale price! I am in the "using" mode right now. My cabinet won't hold anymore.
I know a lot of people really like stashing blenders and patterns that "speak" to them.
My theory: If it feels right, do it. If you feel guilty after you buy it, then maybe its a time to cut back and cut into your stash.