They do have a set of keycaps with media symbols on them, but they're dedicated:
http://pckeyboard.com/page/Buttons/MEDIA
The way they do keycap printing doesn't lend itself to custom work unless you're going to pay them a ton of money- their dyesub printer is really all about printing in volume.
You know, though, the more I look at the Fentek stickers the more I think that's probably the best way to go, particularly after I noticed that they can do top and front stickers. The way those are made, they should be a lot more durable than the P-Touch labels.
The one advantage the P-Touch labels have is that they're clear and can go over any color keycap. You can even print white-text ones, which is something you can't do with Unicomp's system.
I'm thinking that perhaps we should collaborate on this, it may be cheaper for both of us, if doing stickers is what you're interested in doing. Get some Fentek white-on-black stickers, some black vinyl dye and you could make a really cool looking black IBM keyboard for a retro-modern look.
By the way I did look through the one bag of caps and didn't find my goofy Print Screen one, but did find the COPY and UNDO ones which I also didn't use for similar reasons- they just look too different from the rest of the keys to use.
![Crying or Very Sad :cry:](./images/smilies/icon_cry.gif)