We have a similar situation here in the Pine Barrens of New Jersey.
The short answer is that it's not worth the effort. Survival of the tree is very chancy, as those roots go way down before developing feeder roots. Most folks around here have given up on collecting trees growing in sand for that reason.
Having said that, I'm sure that there are pockets of soil with trees in them as well. These can be collected with care and permission.
Andy Smith, of
Golden Arrow Bonsai is a professional collector. You might want to visit his web pages. He also sells a DVD on collecting, including Junipers, mostly in South Dakota.