Have you tried Vistaprint? I love them! Their products and tools are easy to use, lots of creative ideas and patterns.....and great deals! Right now you can get return address labels, business cards, invitations and announcements, rubber stamps, pens.....and more all for FREE! All you pay is shipping, which varies based on which products you choose and the speed of shipping you want. (The 21 day shipping is the cheapest, but in my experience it usually comes faster than that!)
Recently I "bought" return address labels for my two oldest children (because you can get 2 sets of 140 labels for free at a time). I only put their names on them so they could use them to label their belongings - books, folders for school, lunch boxes, toys, etc. They loved them! I let them help pick out the design they wanted and they're super cute! I only ended up paying about $3 for plenty of labels for both kids!
Oh, and before that we bought labels with the darling little caricatures for the family! L.o.v.e these!
*With Father's Day coming up, you could also order something cute for Dad - his own labels to have books returned, tools marked as his, or actual return address labels.