Design your own label, or use this template from Jill Means. I downloaded the template, but it's in PDF form, so you can't manipulate the font at all or add your own text, so I wound up making my own. You really could just download it, then print it out and neatly write your child's name on it with a thin marker. Or better yet, have your child sign it him or herself! Then, you photocopy or print it onto transparency paper. Cut it out, and slide it into the bottle. The soap helps it stick to the front of the bottle so it looks like a label.
Isn't it cute? And inexpensive. Gotta love that!