I turn a lot of pens but it never crossed my mind to add a label. I didn't check the web prices but pen kits at woodcraft are very reasonable. As much as I'd like people to believe that my pens take alot of time and skill, most of them do not. I can crank out Slimline or Euro pens in under 20 mins, from start to finish. The finish process usually takes just as long as the actual turning and can also be done directly on the lathe.
If I can figure out how to add the label and put a nice finish on top, maybe I'll make a few and post some pics. The finish I use now is a mix of SuperGlue (CA glue) and boiled linseed oil & friction which would surely mess up the label. Maybe I'll try just some poly or lacquer..............