I'm not big on the whole thrift/charity shop thang, but I will scour sales at the drop of a hat. My criteria? If the fabric would cost more to make it than the sale price reads AND the time needed to refashion/alter seems reasonable AND I would wear it once changed (!), out comes the credit card.
The shiny gold (plastic!) buttons on this very nice knit fabric top from M&S just had to go. I wasn't going to put anything back on, but the little placket -- despite my careful picking of the stitches -- was left with little holes I knew a trip through the washing machine would not fix.
So, that's new white buttons on for a more subtle look. I had to take it in an inch at each side as well, this having been bough in the winter sales when I was a size or more up due to taking the wrong meds. Well, right meds for a wrong diagnosis, which has been rectified: I'm nearly back to my USA 12 self so feel like sewing and refashioning clothes again after a bit of a break.