hey Rich !
sorry, i knew i had forgotten something ..
* * *
well, i've taken an other look at the maxwell render dosch trees. they're certainly perfectly usable.
but it's a personal issue that i like high-poly meshes better than most of those 5 to 10K poly trees. i've looked at those dosch trees and they all look tailored and seem to have a little too large leafs. they look like miniatures for a doll house .. (sorry

)
maybe check out this link..
http://commerce.vismasters.com/catalog/ ... oduct=4513
i mean i've been working in a landscape architecture office and my bosses always preferred photos over 3d models because of their realism. take a look at a bunch of tree fotos at google (really do it !) and then go back to dosch's pdf and you will see that all those trees look merely symmetric and overly saturated in the greens of their standard textures.
( i always felt that there's nothing more disturbing in an image than overly green plants in a decent render. )
hmm .. i really cannot recommend anything to buy that's the perfect solution. i can just say: decide if you wanna go LOPOLY or HIPOLY.
for lopoly certainly you can buy one of the two mentioned series.
for hipoly go for something more expensive like onyx garden suite (
http://www.onyxtree.com/ ). the HUGE advantage of that you can generate lots and lots of models of the same species and save the models. costs 595 $ though. or natFX, but is even more expensive !
i hope this helps a little !