I bought some pre-made labels at my LQS that are printed on good quality muslin. They have cute sewing machines and different designs around the machines. You can color them with brush tip dye pens. They're kinda big..about 5.5" by 4.5" but very nice. They come six to a package, all on one piece of fabric so you can hoop them for embroidery if you want. The design is by Lonna Nachtigal and the pattern publisher is Block Party Studios, Inc. in Nevada, Iowa. There's no website shown on the package. I haven't used them yet, but will soon.
I've also seen fabric on a bolt that had pre-printed labels ready to be signed.