It was a promotional offer from
DVC a while back - maybe 2005/06 that I believe was for 15% off?? We took the tour during that time but did not buy, however. The only thing I really remember is that SSR was $85 pp with the promotion and that someone who was already a DVC member was supposed to recommend you.
Now, I am not sure if that has been revitalized or not, but I have not heard of it for a while.
HTH