Womack Nursery has mustang grape.

In The Grape Grower Guide by Lon Rombough he talks
about someone who is currently developing pure strains
of rupestris. He died recently, but his wife might
know. Email BunchGrapes.com and ask.

Most strains of pure rupestris are not very
edible though.
But America (Vitis lincecumii X Vitis rupestris)
is pretty good.
It is resistant to Pierce's Disease.
It requires a second variety for pollination.
Sources:
Double A Vineyards, Bunch Grapes.com

Here is a link that might be useful: Garden For Nutrition.org