Is it a check in the mail, or credit on future purchases?

Check in the mail = bonus.

I assume the checks go out only after the 30 day return period has expired.

I'm in the process of helping a friend buy a new system and she liked mine, so we're putting an "Axiom Jr." system together for her. That would be great if I could get her an extra 5% off (I'd give her the referal money, you see...)