You could contact conservation group this group for Sonneratia:http://www.mangrovewatch.org.au/
Araucaria bidwillii can be gotten from Rare Palm Seeds:
www.rarepalmseeds.comI think the Lepisanthes has been offered by a couple of the Indonesian members of this forum, maryoto IIRC. Ditto for Mangifera pajang, Diospyros discolor, Stelechocarpus, Baccaurea, Garcinia,...check the Buy/Sell board
Vitex doniana can be ordered from Silverhill seeds in South Africa. You may have to wait for them to collect it; I know they have offered it in the past.
Hylandia is endangered and is strictly controlled by the Austarlian Gov't; basicall unavailable unless you are a bona fide Botanical Garden.
Xanthoceras from J.L. Hudson:
http://www.jlhudsonseeds.net/The Brazilian and South American species (Campomanesia,Myrciaria, Eugenia leitonia) have been offered by members of this forum from those countries in the Buy/Sell section from time to time.
Good growing
Michael