I agree that you shouldn't pay for mystery shopping, even for someone else to register for you. It is a little time consuming to register with the companies but worth it in the end. Do you want to be put on a list that will fill your e-mail with spam? I use a program called roboform to fill most of the mystery shopping companies information. I found it, and a list of over 100 myster shopping companies, that are free to join at volition.com
I hope this information helps
Mike