i don't print mine, i hand ink them on on acid free card stock paper, then i use spray adhesive to glue the front of 2 postal service stickers to back of them living space between the two to peel back the bottom of them so you cans stick them. then i take exacto blade and die cut them myself.
each one is a one of a kind character and no sticker is the same
aside from those would normally order screen printed diecut stickers thru these guys http://stickerobot.com/