The member discount is not always available. Since it comes from member inventory, MS will not usually offer it unless they are convinced - either from past history or current reservation pattern - that the villa will not be needed for point reservations.
At some times, it is available right at 11 months (usually only weekend nights) and sometimes it's not available until within 6 months and sometimes it's not available at all.
The discount is 25% off the rack rate for the room. It's only available thru MS, who can link the cash reservation to a point reservation. I'd suggest making a cash reservation at rack rate and MS can apply the discount when/if it later becomes available.