CMDR Thor--are you an existing DVC member? If so you would be seeing add on discounts rather than new member ones.
I'd be surprised if a non-DVC member could get such a significant increased discount simply by having a "my disney experience" login ID. It does make sense to me that add-ons would be cheaper than initial buys, since a 100 point minimum for a new buyer is easy to justify given the
point chart, whereas it is harder to justify buying so many points (and paying dues on them) when you are already have a DVC membership.
**Edited to add, I just noticed the minimum for incentives in CmdrThor's chart is 100 points, whereas it is 150 points for the "general public" chart. That makes me suspect the better incentives are definitely only add-on, since 150 was required for new purchaser direct incentives prior to May 13.