Any cash back/discounts for Hilton Gift Cards?

I am taking a church group to a conference this summer, and we have been assigned to a Hampton Inn.

Wondering if there are any sources to purchase Hilton Gift Cards at a discount or with cash back? (I checked my usual suspects- our scrip provider and evrewards.com and found nothing. Search also revealed nothing.)

Unfortunately, because of the way that reservations are handled for this conference, getting cash back through a reservation portal is not possible. Thanks.