Crataegus pubescens stipulacea (Mexican Hawthorn) is listed in this catalog:
http://www.colvoscreeknursery.com/about.html
Click on "Price List", go to page 10, item number 13595

Crataegus aprica is a synonym of Crataegus flava:
http://plants.usda.gov:8080/plants/profile?symbol=CRFL2
Crataegus flava is listed in this catalog:
http://www.mailordernatives.com/
Click on "Trees and Shrubs".

Vaccinium vacillans is a synonym of Vaccinium pallidum:
http://plants.usda.gov:8080/plants/profile?symbol=VAPA4
I didn't locate a source for this one, but you might want to try searching on Vaccinium pallidum or one of the other synonyms. Adding the word "native" or "catalog" or "nursery" might help limit the search to potential sources.

I bought vaccinium vacillans from the Gardens of the Blue Ridge. They have a 100% score on the Garden Watchdog. The plants arrived in great shape!

Here is a link that might be useful: Gardens of the Blueridge