http://www.beldecal.com/ has waterslide decal paper for both inkjet and laser printers. It is available in clear and white (remember, printers do not print white).

Scan what you want into the computer, import it into a word processor and size it accordingly. Do a print on regular paper to make sure everything is correct, then print on the decal paper. Let the decal dry for about 20 minutes, then CLEAR COAT the decal. AFTER THE CLEAR COAT HAS DRIED, CUT THE DECAL OUT. The clear coat prevents the ink from running while you wet the decal.

The inkjet paper costs ABOUT $1.00 per 8x11 sheet.