If you drop it off to a Dealer (with a witness) chances are you will be paying full price. If you want an artist rate it has to be under the artist account. That can be available by contacting me directly or dropping off at the CGC booth.
So after contacting the CGC signature series guy, he said as long as you are the artist it doesn't need to be directly witnessed. You can mail the book in or drop them off at a comic con AND if you're the artist you also get a 12 dollar discount, which is awesome.
Thanks for all the replies guys!
If you are the artist and than there would not need to be a witness. A witness, witnesses the artist signature.