Send in what you want, either sketch on napkin or sophisticated illustration program. They have a person (can't remember their name) that will look at it, put it into their computer format, and you will proof it.
Last time I looked into this, we were looking at about $75 for a silver contast job into an existing Sebenza (They won't anodize on a Sebbie you already own, they will only do the silver contrast). You can get an anodize on an as yet unmade Sebbie with your unique graphic.