I always make my own. 2 1/4 inch, cut on the bias I use a piece of PVC pipe, about 15" long and 2" diameter, and roll the assembled strip around it. Then can feed it easily on to the edge of the quilt.
I'm curious about those of you who say you use 3". If you're attaching it to the front of the quilt first, do you still use a 1/4 seam? Seems like you'd have a lot of extra ... do you fold it all on to the back?