Oct 11, 2016
It looks like we spoke too soon; after turning the vendor API back on for most of the day on October 7th, Bungie turned it back off due to performance issues. In the meantime, this update will enable you to see any vendors that are still on, which have included Xur, Iron Banner, and Eververse (it has varied). Bungie has said once the API is back it should be much faster, but has not yet said when that will be.
I want to apologize for the hassle; hopefully we will be back to full capacity soon!